Nuclear power plants involve numerous systems and equipment, complex system processes, and strict operating conditions. More technical problems in the field cannot be tested and verified directly on the unit, and the cost and price of offline physical experiments are also higher, which is not conducive to the analysis of the root cause of the problem and to determining the solution. The computational modeling simulation technology in the creation of numerical models and the simulation of the problem simulation and so on has more advantages. Early mainstream modeling and simulation platforms are mostly imported from abroad, such as MATLAB and Simulink. With the continuous maturity and wide application of domestic modeling and simulation platforms, they are increasingly used in aerospace, ship, vehicle, nuclear energy, and other fields. The chapter introduces the typical application of the MWorks domestic modeling and simulation platform in some nuclear power plants to introduce the basic usage and precautions of the platform in the analysis of on-site problems and formulation of solutions in the field of technological retrofit.