Abstract: Based on the high-order shear theory, the theoretical study on the bending characteristic of composite grid sandwich panels with soft core materials was carried out. Based on the energy method, the calculation formula of the equivalent elastic parameters of composite grid with soft core material was derived. Based on the high-order shear bending theory, the bending differential equilibrium equation of the sandwich plate was derived, and the Navier method was used to give the theoretical solution of the bending of sandwich plate under distributed load with symmetrically laid upper and lower layers and four simple-supported sides. In the example, the theoretical solution of the typical grid sandwich plate was compared with the finite element simulation with the error of 7.1%, which verified the correctness of the theoretical method. The influence of the parameters such as span ratio of the sandwich panel, thickness of the grid, angle of the laminate composite layer and grid spacing on the bending deflection of a typical composite grid sandwich panel containing a soft core material was also analyzed.