Abstract: The mixed online and offline teaching mode provides a new field and opportunity for the reform and innovation of ideological and political theory course in the new era, and adds favorable conditions and basis for the design of teaching theory and content. The explanation of the main social contradiction transformation in the new era should be based on the PBL teaching mode and the combination of the traditional teaching advantages and information technology, and promote the effective implementation of classroom flipping. Combing with the historical task of new journey, it systematically sorts out the theoretical logic,realistic logic and historical logic of the ajor social contradiction transformation in the new era. Integrating Marx’s theory of communication, to dissolve problems should be started from the development perspective of scientific socialism and the construction of a community with a shared future for mankind, stopped at realizing the core of the all-round development of people. It also should highlight the concept of “great ideological and political”, organically integrate school and society, study and life, thought and practice,and help students realize the transformation from theoretical cognition to belief generation.