Abstract: The influence of reheating rate on the microstructure evolution of C-Mn-Si-Al steel microalloyed with Nb and Ti was investigated. The results show that the martensite matrix is tempered to precipitate cementite during the reheating process. With increasing reheating rate, the precipitation interval of cementite increases gradually, but the precipitation decreases gradually. When the reheating rate is 80 ℃/ s, no cementite is precipitated. The final microstructure is mainly composed of martensite, which is partially self-tempered to precipitate carbide during the quenching process. Moreover, two different inclusions with significant discrepancy in size and morphology are observed, one is block inclusion combined with TiN and Al₂O₃, the other is rectangle inclusion Ti with Nb simple substance as main body.