Abstract: For the needs of more detailed and accurate core modeling and thermal hydraulic analysis, based on the Non LOCA thermal hydraulic analysis code GINKGO developed on self-reliance and three-dimensional core physical code COCO, GINKGO/COCO coupling code has been developed by using Dynamic Link Library (DLL) method. This paper introduces the development principle and implementation of the coupling code, and the international benchmark for main steam line break accident (MSLB) completed by Organization for Economic Co-operation and Development (OECD) is chosen to validate the coupling code. The results show that the calculation results of GINKGO/COCO are in good agreement with the benchmark values. It is indicated that the GINKGO/COCO coupling code is with good computing performance and reliability.