In order to solve the problems of low accuracy, long time for error testing and low automation when peple use traditional instruments to test the error of degaussing equipment. In this paper, the degaussing system error sources and characteristics of degaussing equipment are discussed. It analyzes the feasibility of a common error handling method such as the least squares method and practical filter analysis. Meanwhile it also researches the test methords about degaussing equipment static characteristics, dynamic characteristics, transient characteristics and normality characteristics. This paper studies the algorithms of the system self-correction technology, gives the three stages of data calibration method to eliminate the systematic errors, devises the differential amplifier circuit to suppress the zero-drift phenomenon, Based on virtual instrument technology and Labview platform, according to the proposed test methods and analytical methods, it gives a successful implementation of a degaussing power error testing system.