Heat treatment process of 31Mn2SiREB cast steel used in crawler plates is directly quenching at 1050°C after casting. The reasonableness of the process needs to be surveyed. In this paper, the effect of quenching temperature on mechanical properties was studied, and the micro-area composition and micro-hardness at different quenching temperature were investigated. The results show that tensile strength and impact energy increase observably with the elevating of quenching temperature. With the increase of quenching temperature, the fluctuations of micro-hardness and chemical composition at different micro-areas become obviously small. This means that the relatively homogeneous structure and composition can be acquired in higher temperature. The as-cast microstructure is extremely uneven, so pre-treatment process of normalizing or diffusion annealing ought to be carried out before quenching treatment, and quenching temperature should not be too high.