Austenitic stainless steel is widely used in chemical, petroleum, energy, power and other industrial production due to its excellent corrosion resistance and high temperature oxidation resistance, but austenitic stainless steel is prone to stress corrosion in corrosive media containing Cl- Brittle cracking. The reason for the leakage of the plate heat exchanger is the stress corrosion of the plates. The heat exchanger is exposed to a corrosive medium containing Cl-, which destroys the solid and fine Cr-rich oxide film on the stainless steel surface. Under the long-term effect of the tensile stress caused by the processing residual stress on the steel plate, stress corrosion cracking occurs. In addition, the water vapor contacted by the heat exchanger may not reach the standard, resulting in a high C and S mass fraction in the chemical composition of the heat exchanger and a low Ni mass fraction, which reduces the corrosion resistance of the heat exchanger and accelerates the stress corrosion rate. The three factors related to stress corrosion are material, tensile stress, and environment. As long as any one of the three factors is eliminated, stress corrosion can be prevented.Therefore, the plate heat exchanger should be properly selected materials, correctly assembled, and regularly cleaned to destroy the corrosion generation conditions. Reducing the content of Cl- and other harmful ions in the medium effectively prevents the crevice corrosion at the plate contacts. Ti plate is the best structural material to resist pitting corrosion and crevice corrosion. The stainless steel plate of plate heat exchanger can be replaced with Ti plate if conditions permit. At the same time, it is recommended to comprehensively find out the reason why the plate heat exchanger contacts the corrosive medium, and replace the leaked plate heat exchanger in time.