Abstract: Daya Bay Nuclear Power Plant adopts U.S. Bailey9020 analog control platform and plans to carry out the digitally upgrading during 30-year overhaul. In this project, the target SH-N system, Bailey9020 platform and Daya Bay process simulation model are used to build the verification platform through the PLC interface, and the pressurizer pressure control loop is selected as the verification object. This project takes the startup test program as reference. By comparing the response differences of the same disturbance on different platforms, it verifies the applicability of the current control parameters of Daya Bay in the target DCS platform, and finds the inherent defect that the proportional function of the PI controller of bailey9020 platform cannot respond when conducting the manual/automatic switching. The corresponding optimization measures are put forward from the aspects of circuit design and operation program. This project achieves the purpose of analog board analysis, DCS configuration verification and constant value conversion, and provides important feedback for the current Daya Bay unit operation.