In this study, we focus on the effect of solid-solution treatment on the susceptibility to intergranular corrosion and electrochemical corrosion of 304 stainless steel. The results show that with the solution temperature rises, the grain size of the steel increases and the intergranular corrosion tendency decreases. After corrosion, it exhibits a step microstructure and grooves at grain boundary on surface of the steel. The corrosion resistance of the steel can be improved by means of properly increasing the solution temperature and choosing a faster cooling way such as water quenching. Besides, with the nitric acid solution temperature rises, the corrosion current (Icorr) increases and the pitting corrosion potential decreases, in which pitting corrosion is more likely to happen. Moreover, in high concentration of nitric acid, a stability passive film can be formed on the surface of 304 stainless steel, which prevents the reaction of the anode, lowers the corrosion, and shows a better anti-corrosive ability.