In the Stationary Digital Breast Tomosynthesis(s-DBT) system, the role of the focusing electrode is to obtain clearer scanned images by focusing the electrons emitted by the carbon nanotubes. As one part of the control system of the s-DBT, the real-time control system of the focusing electrode high voltage power supply is designed. The control system using the NI CompactRIO device and LabVIEW as platform. The hardware unit mainly includes NI CompactRIO 9068, analog output module NI 9263 and analog acquisition module NI 9201. The software design includes the allocation of I/O ports, the choice of CompactRIO development architecture, the design of the power supply control’s flow chart and the generation of dynamic link library. Through the construction of the test platform, the control system's feasibility and reliability were tested, analysis of the experimental data shows that the control system’s relative error of the high voltage power supply’s voltage control is less than 0.5%.