The first stage principle absorber, which is often used to purify crude oil or highly acidic natural gas, is the core equipment of petrochemical enterprises. Uniaxial strength check considering axial stress, hoop stress and radial stress is the main design idea of high pressure vessel. However, absorber integrity issues due to corrosion, thermal stress and residual stress caused by welds can cause absorber deformation, strength degradation and even explosion. In this paper, mathematical models for absorber strength degradation due to corrosion and thermal stress are established. Another finite element model by element activation is established to evaluate the residual stress caused by welding process. According to parametric study, the effects of various parameters on residual strength of damaged absorber are studied. Strength check is carried out based on Lame thick-walled solution and von Mises yield criterion for the absorber according to the stress distribution of absorber considering corrosion, thermal stress and residual stress under tri-axial stress. Finally, accuracy of the mathematical model and element model of the effect of corrosion, thermal stress and residual stress on residual strength is verified according to actual service environment of absorber. The research results presented in this paper can offer a technological basis and theoretical foundation for residual strength evaluation and absorber design of first stage principal absorber with weld considering corrosion and thermal stress in sour environment.