The present study sought to investigate the effect of passivation temperature on the defects present within the passivation film and the corrosion behavior of 304 stainless steel in a multi-component organic acid system. To this end, electrochemical testing techniques were employed to analyze the electrochemical behavior of the passivation film within the temperature range of 30-80 ℃. XPS analysis was used to characterize the composition of the passivation film, and quantum chemical calculations were performed to study the mechanism of passivation in 304 stainless steel. The findings suggest that at temperatures below 60 ℃, as the temperature rises, the corrosion potential shifts in a positive direction, the self-corrosion current density declines, and the polarization resistance increases. Concurrently, the donor density decreases, the film density increases, and corrosion resistance improves. The passivation film of 304 stainless steel consists primarily of metal oxides, including Fe2O3 and Cr2O3. A polycarboxylic acid environment has been shown to promote the enrichment of high-valent oxides, resulting in a more stable structure compared to natural passivation films. Polycarboxylic acid molecules have been observed to accept electrons readily from the metal, forming a stable chemically adsorbed layer on the surface of 304 stainless steel. This process effectively achieves passivation protection.