Abstract: rogrammed remote control and monitoring system of a KYS 550A/90V silicon controlled power supply with high current stability is described. The magnetic spectrometer excited by this power supply is used for electron scattering experiment in the medium energy region. With this system, the power supply can be turned on and off by computer or manually, the output current can be set and monitored, the operating condition of the KYS power supply can be displayed and the relevant data can be acquired and processed. The setting resolution of the system is 12 bits. The long-time stability of the output current is improved from the original value of 8×10~(-5)/24h with the local control system to 3×10~(-5)/24h with the remote control system. The system has the following characters: high reliability, small size, low cost and high ratio of performance to cost.