Efficiency is an everlastingissue which is of special importance toany economic society . In the modern market economy society,inefficiency means losing competitiveness . It is imperative for cooperatives toimproveeconomicefficiency,thus maintaining theircompetitiveness .Generally there are two aspects in the concept of cooperative efficiency . On the one hand,it can be understood as cooperative input-output efficiency,which means to obtain maximum output at a certain level of input,or to realize minimuminput at a certain level of output .This belongs to internal efficiency for cooperatives . On the other hand,it also can be regarded as external efficiency for cooperatives,which means the comprehensive efficiency of cooperatives in promoting reasonable allocation of social resources among various departments while pursuing internal efficiency . In short,external efficiency refers to cooperatives'contribution to total welfare in society . However,the external efficiency for cooperatives,in other words,the ideal Pareto optimality,does not exist in reality and it would be difficult tocarry on quantitative evaluation .Therefore,it is realistically reasonable for cooperatives to pursue input-output efficiency . The cooperative efficiency is determined by the chosen objective function .Cooperatives with different functions have different objective functions . For example,objective functions for marketing cooperatives and for purchasing cooperatives are different . Identical objective function is the basic premise for measuring cooperative efficiency . It is an accidental phenomenon for cooperatives to realize efficiency because of information asymmetry,poor management etc . Generally inefficiency manifests in cooperatives . Therefore,there is practical significance of adopting effective methods to measurecooperative efficiency accurately and in discussing profound reasons affecting the efficiency . The influence of scale on cooperative efficiency is obvious .It is generally believed that there exists an optimal scale for each cooperative,with which the cooperative can reach its maximum efficiency .It also should be noted that cooperatives need an appropriate scale,which may grow bigger with the expanding of social-economic scale .Only the cooperative has dynamic adaptability in terms of scale can it achieve higher efficiency in increasingly fierce global competition . Internal control factors have essential impact on cooperative efficiency .Among thesefactors,staff structure and manager's human capital are the most important ones . To some extent,the process of improving cooperative efficiency is the process of constantly improving staff and manager's quality and ability . It is also clear that a certain size of board members and the supervision of certain members from supervisory board can improve cooperative efficiency . The external environments such as institution,resource and market also affect resource allocation and utilization in cooperatives though influencing internal control factors,and then affect cooperative efficiency . Therefore,a cooperative which can achieve input-output efficiency has to rely on the coordinative operation between internal control mechanism and external environments . As far as policy is concerning,investment on staff,including managers,is the key to improve cooperative efficiency . Given the fact that most staff members in Chinese cooperatives have weak cooperative awareness and are incompetent in management,investing on them is especially significant .In particular,the approaches to promote efficiency of cooperatives include improving staff's human capital by education and training and improving their cooperative awareness,discussion competence,managerial capability,and response to environment . In addition,it is necessary to consider the role of external environments .Besides continuing to perfect relevant laws and regulations and creating a better institutional environment,other factors such as regional resources environment should also be taken into consideration . It is important to adjust policies to accord with different resource factors in different regions in order to produce a positive incentive effect on the development of cooperatives .