Ball mill load parameters are important indicators to determine the quality and efficiency of grinding work. In order to improve the operation performance of the ball mill load parameter soft measurement system and reduce the comprehensive measurement error, a ball mill load parameter soft measurement system is designed by using asos-elm algorithm from two aspects of hardware and software. Add a ball mill working data collector, refit the processor and output display screen, expand the memory space, use the power circuit to connect the hardware equipment, and complete the design of the hardware system. According to the structure and working principle of the ball mill, a mathematical model of the ball mill is built. Under this model, the vibration signals of the ball mill under different working conditions are collected. Using asos-elm algorithm, the characteristics of vibration signals are extracted, and the soft measurement results of ball load, material load and water load parameters of ball mill are obtained. The design of soft measurement system for ball mill load parameters is realized. The system test results show that the comprehensive measurement error of the designed system load parameters is reduced by about 0.064kg, and the system performance is significantly improved.