To select the suitable thickness of heat insulating material for the bulkhead of reefer ship for agricultural products, a steady state three-dimensional mathematical model of bulkhead is set up in this paper. The calculational conditions of the heat transfer model are defined according to the heat transfer process and reasonable simplification. Numerical simulations are performed using computational fluid dynamics (CFD) software PHOENICS as the thickness of heat insulating material, rigid polyurethane foam, is different. The obtained temperature distributions of the model in each case are analyzed. The suitable thickness is pointed out according to the effect of the thickness of heat insulating material on heat transfer property of the bulkhead.