The cracking problem of domestic turbine housing in the development process of vehicle turbocharged gasoline engine was studied. The cracking failure factors were comprehensively analyzed from the aspects of material, production process and test design. Then the fluidsolid coupling analytical model of turbine housing was established and further optimized with the thermalmechanical fatigue analysis method. The heat transfer boundary of turbine housing was calculated by CFD method, its transient temperature field in a periodic thermal cycle was then solved and its transient strain change in the cycle was finally acquired by inputting the calculated transient temperature result into FEA model. According to the variation of strain, the risk of thermalmechanical fatigue cracking could be estimated. The optimization scheme of replacing imported A3K turbine housing with domestic 1.4837Nb one was put forward and verified by the engine cold and heat cycle endurance test. The results show that the proposed method is feasible to solve the cracking problem and can meet the engineering requirements.