Abstract: Traditional stress measurement methods are time-consuming and destructive. Ultrasonic stress measurement method was used to overcome these disadvantages based on the acoustoelasticity theory. Ultrasonic stress measurement experimental equipment was established with Lcr waves. This method has proved its accuracy and reliability by actual measurement of such industrial structures as electric multiple units(EMU) and rockets. The entire envelope weighting algorithm was proposed to reduce the influencing factors for measurement accuracy, by which uncertainty of the system is lower than threshold method.