The influence of stamping speed and constraint conditions on the forming quality is studied in the stamping forming process for thin-walled square metal pipe as an object. Studies show that increased constraints on the pipe wall of thin-walled square metal pipe can raise the overall stability of compression deformation in the stamping process. It can obviously decrease the pipe wall flexure by using some measures, such as setting baffle on side wall and filling sand in inner cavity. Suitable stamping speed can effectively eliminate flexure of top wall of the thin-walled square metal pipe. Reasonable stamping process parameters, such as stamping speed and constraint conditions, can effectively improve the stamping forming quality of thin-walled square metal pipe.