Bimetallic composite pipe consists of a CRA layer for corrosion resistance and carbon steel for mechanical properties, which shows a promising prospect of gathering pipeline with its effective-cost and reliable corrosion resistance. However, the corrosion resistance of composite pipe is determined by the quality of its welding gap. In order to investigate its anti-electrochemical corrosion performance, Corrosion tests of X52/825 welding gap were performed in a stimulated gas field solution containing both 1 MPa CO2 and 1.5MPa H2S at 70℃ for 720h in a self-designed high temperature and high pressure (HTHP) autoclave. The anti-stress corrosion cracking(SSC) performance of X52/825 clad pipe ring root welding gap was investigated in both NACE A solution and the stimulant gas field solution by Four Point Bending (FPB) testing and Constant Load (CL) test. Then the experiments were rerun in Tiandong 5-1 high sour gas well. In addition, the alloy diffusion and microstructure characteristics of TIG welding gap were analyzed through SEM and EDS technologies. The results reveal that the root welding gap is almost not corroded in the stimulant gas field solution and no micro-cracks observed by electron microscope. Anti-SCC test results show the root welding gap does not get broken, indicating a good resistance to environmental-cracking in H2S/CO2 environment. The transition layer can be obviously observed in the root welding zone, and the alloy content of transition layer is diluted. However, the transition layer does not stretch to the inner of CRA layer, which illustrates its good anti-corrosion performance. Therefore, TIG welding technology can be well used in the welding process of composite pipe, which can provide theoretical reference for manufacturing and application of clad pipe.