Abstract: As the computer technology was widely used in nuclear power plants,a lot of unpredictable problems happened in the process of DCS（Distributed Control System） replacing the traditional relay rack.In this paper,considering the practical situation of Fuqing nuclear power DCS project,the typical problems in non-safety class of DCS software,which appeared during testing and commissioning process,are analyzed and the solution plan is proposed to obtain the experiences for the operation and commissioning activities in the future.