Through the investigation of the history of thought,it can be revealed that there are important differences between Marx’s criticism of Hegel’s speculative philosophy in Critique of Hegel’s Philosophy of Right and Paris Manuscript. In Critique of Hegel’s Philosophy of Right,Marx,deeply influenced by Feuerbach’s critical speculative philosophy,launched a fierce attack on Hegel’s speculative philosophy from the aspects of the reversal of the conceptual subject and the real subject,the identity of the conceptual contradiction rather than the solution,and the mystification of the relationship between experience and speculation. But in Paris Manuscript,Marx changed his attitude and position of strongly criticizing speculative philosophy in the past,and recognized the positive significance of Hegel’s speculative philosophy (speculative dialectics) while highly affirming Feuerbach’s philosophy,that is,it regards man’s self-production as a process,a process of self-promotion and self-creation. Within the scope of alienation,this speculative philosophy has grasped the dialectical movement of real human life,which has a critical form. In the process of thinking,it connects the links of the development of things with the whole of things organically. To grasp Hegel’s speculative concept and method,we need to go back to the explicit elaboration in Phenomenology of Spirit and Little Logic. In the former,Hegel argues that the main task of speculative thought is the expression of truth,that is,the dialectical movement of things,the process by which things arise of their own,develop of themselves,and return to themselves. Speculative thinking shows its strong sense of life and reality. In the latter he holds that speculation is only the law of reason through thought,that is,the law of affirming reason. Unlike dialectics,which contains the negation of oneself in the affirmation,the speculative stage strives to sublate this negation,and is the law that contains the affirmation in the negation. In the criticism of political economy later,Marx made a new materialist transformation and scientific application of Hegel’s speculative method. In the transformation of the speculative subject,Marx transformed the “impersonal reason” as the subject in speculative philosophy into the real person and his activities in the social relations. In the transformation of speculative process,Marx transformed the conceptual self movement in speculative philosophy into a consistent speculative movement of logic and history. In terms of the transformation of speculative results,Marx transformed the concrete totality in Hegel’s speculative philosophy,which is the result of thinking and the actual process of the development of things,into the concrete totality as the result of thinking grasping the development process of real things. From this point of view,we can see that in the process of constructing scientific political economy,Marx did not blindly negate and abandon Hegel’s speculative method,but tried to sublate and transform this speculative method in combination with the study of modern capitalist society,and applied it to the grasp of the category of political economy and its logical order.