High-performance optical digital calibration device helps to improve the reliability and efficiency of electronic transformer combined unit. Aiming at the problem of communication packet processing capability and synchronization of electronic transformer merging unit test, an optical digital calibration device based on FPGA and DSP is designed. The optical digital calibration device design principles and technical difficulties are analyzed. The design scheme based on FPGA and DSP is studied. The concrete components of FPGA, Blackfin DSP and man-machine interface are introduced in detail. And then the processing flow of FPGA and Blackfin DSP is studied in depth. Finally, the optical digital calibration device and the digital power test platform DRM perform joint test. The test results show that the optical digital calibration device based on FPGA and DSP can not only meet the functional requirements of the unit test, but also has good real-time performance. This work is supported by Science and Technology Project of State Grid Fujian Electric Power Company (No. 521304150043).