The 2.25Cr1Mo steel that was frequently used in petrochemical equipment was welded by hot welding process at 750 ℃ and 850 ℃. The welding residual stress of every welded specimen was measured by the small blindhole method. The electrochemical workstation was used to measure the stress corrosion property of every welded specimen in alkaline, acidic and neutral medium. The microstructure of welded joint was analyzed by metallographic technique. The results showed the hot welding process could obviously reduce the welding residual stress of 2.25Cr1Mo steel welded plate and raise the stress corrosion property of it in every medium. In addition, the higher the process temperature was, the bigger the reduced degree of welding residual stress was, the more the stress corrosion property was improved. At 850 ℃, the welding residual stress was reduced by the degree of above 60% and the stress anticorrosion property was raised by the degree of above 30%. The microstructure of welded joint was improved after high temperature welding. The mechanical property was maintained.