Abstract: In order to solve the problems of aging of core cooling monitoring system, and the unstable work and the flash failure alarm of CCMS due to unavailability of some old parts in Daya Bay Nuclear Power Station, the modification of the whole upgrading program is proposed. The design of new CCMS using localization instrument control platform（Firmsys） is described. The research and analysis for the key technology of new CCMS function and interface is done. The installation and commissioning stage of handling technical problems and the solution is described. The new system has been functionally verified. Finally the independent design and renovation of CCMS is realized.