The invention provides a simulation system and method for water logging in a building. The method comprises the following steps: firstly, carrying out a typical situation physical model test accordingto research conditions; modeling a hydrodynamic mathematical model based on an SPH method, and carrying out calibration and verification on the hydrodynamic mathematical model by adopting a physicalmodel test result; carrying out water logging event numerical simulation calculation by adopting the verified mathematical model; and analyzing and processing a numerical calculation result to obtaina water logging characteristic and a water body movement process three-dimensional demonstration animation. The water logging three-dimensional dynamic process is simulated through the gridless smoothparticle dynamics method, the method is suitable for calculating the large deformation problem of the liquid level, and the defect that distortion is likely to be generated when the gridding method tracks the free liquid level under the complex conditions of water overturning, crushing and the like is overcome. The nuclear island plant building is complex in structure and large in calculation amount, the method solves the problem of calculation efficiency through parallel calculation, and accurate calculation of water logging in the nuclear island plant building is achieved.