The performance of Instrumentation and Control System is critical for nuclear power plants. Now the Instrument and Control System of domestic nuclear power plants mostly uses the analog control,in which the precision of data displaying and automation are poor.This paper introduces a data acquisition sys- tem applying in Qinshan unitⅢreactor shutdown system,which incorporates the technology of DCS to realize the function of quick data acquisition,save,alarm,query,displaying and improve the safety and econ- omy of nuclear power plants.