Abstract: Verification and validation (V&V) is very important for the software quality assurance. Reasonable and efficient V&V strategy can achieve twice the result with half the effort. Core and system integrated engine for design and analysis (COSINE) software package contains three reactor physics codes, the lattice code (LATC), the core simulator (CORE) and the kinetics code (KIND), which is called the reactor physics subsystem. The V&V strategy for the physics subsystem was researched based on the foundation of scientific software’s V&V method. The module based verification method and the function based validation method were proposed, composing the physical subsystem V&V strategy of COSINE software package.