The invention relates to a method for determining the flexural capacity of a sandwich plate with non-metal surfaces. The panel of the sandwich plate is made of non-metal materials. The method for determining the flexural capacity of the sandwich plate with the non-metal surfaces comprises the following steps of: acquiring the relevant parameters of the sandwich plate with the non-metal surfaces, determining the deflection of the sandwich plate with the non-metal surfaces, and determining the flexural capacity of the sandwich plate with the non-metal surfaces. By considering the influence of the rigidity of the non-metal panel on the flexural deformation of the sandwich plate with non-metal surfaces, the method for determining the flexural capacity of the sandwich plate with the non-metal surfaces precisely obtains the deflections of the sandwich plate with the non-metal surfaces under the concentrated load and the uniformly distributed load and then determines the flexural capacity ofthe sandwich plate with the non-metal surfaces by the deflections. By the invention, the flexural capacity of the sandwich plate with the non-metal surfaces is precisely obtained, thereby determiningthe flexural mechanical properties of the sandwich plate with the non-metal surfaces and precisely estimating the safety performance of the sandwich plate with the non-metal surfaces.