In a simulated primary circuit of PWR environment, the effect of temperature on Stress Corrosion Cracking (SCC) of 304L stainless steel in high-temperature and high-pressure water was investigated using Slow Strain Rate Tests (SSRT). And the fracture morphology of specimens was analyzed with the aid of Scanning Electron Microscopy (SEM). The results show that 304L stainless steel tends towards a brittle fracture as temperature increasing. Certain parameters, such as tensile strength, almost remain unchanged, while both elongation and section shrinkage slightly decrease. During the test, no obvious cleavage character is found on the fracture surfaces of 304L stainless steel specimens. With temperature increasing from 200℃ to 345℃, no sensitive temperature is found for 304L stainless steel and the susceptibility to SCC is low.