In order to reduce power consumption of residual oil hydrogenation reciprocating compressor K-4001A, save energy and reduce overall cost of compressor operation as far as possible, it is necessary to analyze the uselessness reason of stepless load regulation system in the reciprocating compressor and take appropriate measures for solving the problem. It is found through analysis that the main reasons are incorrectness of the selected value of low selector, incorrectness of logic of relay controller works and design defects of compressor system, which result in secondary and tertiary control failure to gas load regulation. After the above-mentioned factors are eliminated, K-4001A stepless load system operates normally and power consumption is greatly reduced accordingly.