The maximum theoretical pressure value of the punch during the clinch joining was explored. Aiming at the shortcomings of the existing quality control method, Taking the 5×104 N servo press as the hardware platform, a set of quality monitoring system with data acquisition system was designed. Using the minimum error control law, the monitoring windows were set. Test results show that the quality monitoring system can not only collect the data of pressure and displacement and draw a curve for realtime display ,but also determine whether the clinch joining is qualified and alarm. The computed maximum pressure matches the experimental value well.