Abstract: Effect of sensitization on stress corrosion cracking(SCC) of 304L stainless steel in NaOH solutions with different concentrations at high temperatures was investigated by using slow strain rate tests(SSRT) and SEM technology.The results show that after sensitization,the resistance of the steel to SCC declined remarkably under the conditions of different temperatures and concentrations in NaOH solution.The effect of temperature was more obvious than that of the concentration.The main reason which resulted in the property reduction was the carbide precipation along the grain boundaries after sensitization and the formation of chromium depleted zone.