The first populist wave appeared in the Western world in the 1860s, and, like a ″spectre″, populism has never been out of the world stage. In the 1950s, the second populist wave came into being in Latin America. Since the end of the 1980s, the third populist wave has been in flood in Europe and America, which is still in development now. In recent years, most European parliaments have populist parties and their representatives. Populism is more popular in the USA, as is proved by Trump's winning of the White House. However, as one of the basic concepts of politics, populism doesn't have a universally accepted definition. ″Populism″ in essence expresses the dissatisfaction of people with the present governments and politics in the Western world. Although it is difficult to define populism in a perfect way, its core value is clear - it's a theory of the people, and it's a movement for the people.  ″People″, ″elites″, and ″the general will″ are three key words of populism. Elites ignore people's appeal or the public will, inducing people to fight against them. In addition, the distinction between left and right wing populism should be discussed, as it is one of the issues raised by the third populist wave. The right-wing populism allows social difference and inequality, and emphasizes the inequality, which is closely related to xenophobia, racism and welfare chauvinism. But the left-wing populism tends to eliminate the differences among the people, in terms of social ideology against neoliberalism, globalization and everything that might cause the wealth inequality.  The third populist wave, as a political and social force, has swept over the Western world, leaving a profound influence on the whole world. Brexit and Donald Trump's presidency may be a good justification. The negative effects brought by the defects of globalization and neoliberalism are the direct reasons for the burst of the third populist wave. The defects of globalization and the continual economy crisis decay the middle class and the blue-color class, and populism suits their needs.  Even as it is, the inducement of the third populist wave is the agitation of the social and cultural agitation of the bottom in society. The agitation is visualized in the concern of the identity recognition of Caucasians, the crisis of immigration, the threat of terrorism, and the passive consequences of separatism. In supplement, the third populist wave shows not only the predominance function of social and cultural factors, but also the influence of political factors and the media. In a word, the reasons for the third populist wave are rather complex. Besides factors in economy, politics and media, we should pay attention to the cultural backlashes in the wave. The issues such as minorities, immigration, terrorism, EU integration are major ones to attract citizens, and they may vote for their own interests and ideas. Unlike the first two waves, the third populist wave reveals many new features. Firstly, the social basis of the third populism wave changes, expressing different social positions and political orientations. Secondly, the third populist wave, especially the right-wing populism, expresses the influences of social factors rather than economic factors towards modern politics. Thirdly, the third populist wave is not confined to the bottom of the society. It is shown in different levels of power. Economic factors and politicized social cultural factors merge at the same time and the left and the right wings of the populism rise at the same time, which results in an interactional populism at three levels: a populism in social groups, a populism between social groups and states, a populism between state and super-state levels. Fourthly, the third populist wave is much more influential than the previous ones. The populists in the third wave have won a great success, or even reached the supreme power in some countries. Fifthly, this wave is closely related to extremism or radicalism, but it will never turn to fascism or Nazism. Besides, this populism should be clearly distinguished as a political doctrine and a social movement. The criticism on populism, elitism, dictatorship and irrationality is caused by regarding populism as a realistic political movement, although in reality populism does have such troubles. However, populism is of great importance regardless of its natural defects in moral standard. In practice, it raises the topics to the front ignored by mainstream parties or politicians, expressing people's doubt on the universal values dominated by the Western world. It hopes authorities and decision makers will hear the ″painful appeal″ from the people. The wider gap between the establishment and the people there is, the more powerful this burst will be. When we take populism as a supplementary towards democracy, we will go beyond the parochialism assuming populism as a political movement, whereas the emphasis on popular sovereignty is the foundation of contemporary democracy.  As long as there is a deficit in this democracy, the pride of the elite and the indifference of the intelligentsia, there will be a return of people's power marked by populism, it is the revival of the people. Ignoring the people's interests, betraying people' will, will betray the ideals of political civilization. In this sense, the warnings of the populism to the Western democracy will never end. We should welcome rather than reject this wave flooding all over the world.