Structural mechanics is one of the professional foundation courses for the civil engineering, railway engineering, hydraulic engineering, and plays the role of bridge between the foundation course and the professional course. The structural mechanics course of Beijing Jiaotong University is firstly approved to be first-class course in 2020, which indicates the course construction and the talent cultivation are in a new stage. In order to find a way out of the problems and difficulties during the construction of structural mechanics, the "3E+3E" engineering teaching idea following "first emotional perception, then rational exploration" is proposed, in which the moral cultivation plays the guiding role, the diversified and distinguished engineering talents with innovation spirits is taken for the cultivating goal, and improving high level course, highlighting innovation, and increasing challenge level are the basic requirements of course construction. With the ideological and political education, optimization of teaching objectives, innovation of teaching methods during the teaching process, the first-class course construction of structural mechanics is explored. Teaching practice shows that "3E+3E" teaching idea provides the new thinking for the construction of "ideological and political education" and "high-level, innovative and challenging course", creates the conditions for realizing the talents training with knowledge, capacity, and quality, and explores an advantage approach to teaching transform from "imparting teaching" to "inquiry teaching".