This paper aims to improve the quantitative weighing accuracy of packaging process, and design a weighing signal processing method by combining kalman filtering algorithm and fuzzy control principle. Quantitative weighing control system is generally composed of touch screen, controller, weighing sensor, inverter and other electrical equipment. Taking sensor signal processing as the main research object, an improved kalman filtering algorithm is proposed. Kalman filter is used to deal with random noise in weighing signal. A fuzzy controller is used to monitor the difference between the actual variance and the theoretical variance after each update of kalman filter. Finally, an experimental study is carried out. The experimental results show that the actual performance of the improved Kalman filter is relatively ideal, and the maximum weighing error can reach 2.5% before filtering. After filtering, the maximum weighing error is only 0.26%. The signal processing method can effectively reduce the weighing signal noise and improve the weighing accuracy.