Curriculum-based ideological and political education is an important way to cultivate people with virtue, cultivate successors for socialist construction, and adhere to the Sinicization of socialism. The blended teaching model is constantly evolving, and it is considered to be the main form of teaching in the future. To realize curriculum-based ideological and political education, blended teaching environment has its unique advantages. This paper first introduces the connotation and significance of curriculum-based ideological and political education in the construction of colleges and universities. It meets the requirements of cultivating people with virtue, cultivating socialist builders and running socialist universities. Then, the advantages of ideological and political education in online + offline courses in blended teaching environment are analyzed. Finally, taking civil engineering as an example, the design is carried out from three aspects: design ideas, teaching process and teaching assessment, and the ideological and political education mode of the curriculum in blended teaching environment is explored. The concept of blended teaching environment has developed rapidly in China, and new platforms and new applications are constantly expanding blended teaching, but it is less applied in actual teaching. For the discipline of civil engineering, in blended learning environment, this paper attaches importance to the function of moral education in design ideas, teaching process and curriculum assessment of professional teaching, makes use of the advantages of blended teaching environment, integrates ideological and political education into educational goals, integrates ideological and political points into education, takes ideological and political effects as the effect of curriculum assessment, promotes the integration of professional knowledge and ideological and political education in the process of online + offline teaching, improves process-based teaching assessment, and proposes online and offline teaching schemes. It meets the requirements of integrating curriculum-based ideological and political education into civil engineering professional education, achieves the feedback loop of mutual promotion between professional courses and ideological and political education, and gradually forms a model of ideological and political education in civil engineering.