In the period of Rheinische Zeitung, Marx's attitude towards reason changed from firm faith to suspicion in the ″material interests problem″. The change is not only an important development in Marx's thoughts, but also an initial ″seed of thoughts″ that led Marx to open the way of constructing his own ideological system after quitting Rheinische Zeitung. Before encountering the ″material interests problem″, Marx held a firm and highly supportive attitude towards the ontological value of reason, believing that reason is the inherent nature of things and the correct way of looking at things. He regarded reason as the highest standard of examining and judging whether all aspects of reality and reality as a whole are reasonable and legitimate. Marx affirmed that human nature is reasonable and free existence, stressed that philosophical research is the embodiment of free reason in human behavior. He criticized the new press census for trampling on reason and advocated that a free press was a realistic expression of reason. While Marx affirmed and respected reason, he also deepened his understanding of reason itself. Thus, he strengthened his understanding of the relationship between thought and reality, philosophy and the world, rational criticism and the interests of the masses. It laid the ideological foundation for realizing the change of reasonable attitude after Marx encountered the ″Material interests problem″.  On the basis of affirming the primordial position of reason and its decisive role, Marx got into the dilemma of the ″material interests problem″ by participating in the social reality and reflecting on the social reality problems. The ″material interests problem″ is mainly manifested in expressing opinions on wood theft and real estate analysis, the poverty situation of Moselle farmers, free trade and protection tariff. The ″material interests problem″ also fully demonstrates the objective fact that material interest dominated reason. However, there are many controversies in the academic circles on the question of why Marx felt embarrassed about the ″material interests problem″ in the period of the Rheinische Zeitung, and those controversies include ″the theory of lacking knowledge″, ″the theory of conflict″, ″the theory of Ideological dogmatism″. The real reason why Marx felt embarrassed about ″material interests problem″ was the result of the combined action with two factors, including the ″lack of relevant knowledge in the field of political economy″ emphasized by ″the view of lacking knowledge″ and ″the conflict between reason and material interests ″ stressed by ″the view of conflict″. After encountering the ″material interests problem″, Marx was faced with the dilemma of solving the ″material interests problem.″ By affirming the legitimacy of reason and revealing the illegality of material interests, he temporarily solved the ″material interests problem″ in theory. However, in the face of the social reality, Marx actually felt the destructive force of selfish material interests. He was deeply aware that material interests occupied a dominant position in real life and found that material interests became the decisive force to define the scope and norms of national activities. Therefore, Marx began to doubt reason. The doubt of reason provided Marx with an opportunity to reflect on and criticize the Hegelian view of the state and philosophy of rights after withdrawing from the Rheinische Zeitung. The ultimate destiny of reason in Marx philosophy is the end of ontological value and the true manifestation of value in human cognitive ability.