35 CrMoV steel is widely used in industries. To select the best technology for improving the mechanical properties, a series of heat treatments were tested. Metallographic examination indicates that the microstructure is a kind of non-typical bainite and, to a certain extent, similar to tempered troostites. TEM observation shows that rod-like alloying cementite distributed in ferrite grains laid parallel to each other and ultra-fine alloying carbides also dispersed in the lath-like ferrite grains. Moreover, there exists high density of dislocation tangles and microtwins. Detailed discussions are made on the solid solution strengthening, the work hardening process and the crack propagation by view of microstructure, defects and stress concentration.