Combine harvester is a large-scale multi-functional agricultural equipment integrating functions of picking, conveying, threshing and separating, and its working mechanism and electrical system are complicated. According to statistics, when the harvesting machinery works in the field, the fault of the electrical system accounts for about 30%, and there are even fire accidents caused by electrical failures. Therefore, the harvester should comprehensively diagnose its electrical system performance before leaving the factory to improve the quality of the combined harvester and reduce the accident rate. In this paper, according to the needs of the detection of the combine harvester production off-line, electrical detection parameters are proposed and an overall plan for the electrical system performance test stand is formulated. The current and voltage detection methods are used to detect the electrical parameters of the whole machine. The starting current curve evaluation method is used to detect the engine startup parameters. In order to verify the feasibility of the test stand, on-site verification tests were carried out on the combine harvester production line, and a comprehensive test was conducted on the detection efficiency, static parameters, and dynamic parameter detection flow of the whole electrical system. Off-line tests show that the test stand can meet the rapid detection requirements of the electrical system of the combined harvester production line, improve the detection efficiency.