RS485 is a communication platform with high noise suppression capability, high efficiency transmission rate, wide transmission distance and wide common mode range, so it is used as the main communication mode of power meter reading system. In order to detect the working performance of the RS485 bus of the meter reading equipment, this paper designed and developed a RS485 bus interface performance tester for the set terminal and the intelligent meter interface test. The tester consisted of hardware and software components, with high-precision AD sampling and real-time data storage and analysis functions, to achieve accurate performance of the meter communication line and accurate analysis of online fault. The actual test data has showed that the measured parameters of the RS485 bus were less than 5%, which can meet the requirements of the intelligent bus performance test. Compared with the traditional interface performance test method, the detection time and cost were effectively reduced.