In order to study the influence of machining residual stress on thin-walled structure deformation of titanium alloy, a 2D cutting model was established by using finite element software to analyze the influence of feed per tooth and tool edge radius on machining surface residual stress. The deformations simulation of thin-walled parts were carried out by using the residual stress obtained from cutting simulation; the closed cavity side wall milling tests were carried out with feed per tooth of 0.06 mm and 0.08 mm. The results show that compared with the measured value, the simulation surface residual stress error is about 20%, the maximum deformation error is about 12%.The proposed method has certain reliability and feasibility.