The invention discloses a numerical simulation method of planar solid oxide fuel cells. The method includes the steps that 1, performance parameters of planar solid oxide fuel cells are globally defined; 2, 3D simulation models of planar solid oxide fuel cells are established according to geometric dimensions of cells inside a battery pack, physical fields are selected for the 3D simulation models as required, known parameters are input to the physical fields, and 3D simulation models with physical field parameters are obtained; 3, mesh generation is conducted on the 3D simulation models with the physical field parameters, stable-state solving is then conducted, stable-state operational data is obtained, post-processing is conducted on the stable-state operational data, and the required condition curves or 3D images are obtained. According to the method, parameterized structural design is conducted on SOFC, rapid modeling is achieved, and the efficiency of SOFC optimization design is improved.