This paper is concerned with the three-dimensional thermal lattice Boltzmann BGK model which can be applied to the numerical analysis of fluid motions. In the model proposed here, the local equilibrium distribution of microscopic particles is represented more simply than some previous lattice BGK models. In the numerical simulations of three-dimensional fluid flows to examine the feature of this model, the viscosity and the one-dimensional propagation of shock wave appear appropriately, compared with the other numerical results. In the unsteady shock wave flow around the cubic body, the reflection can be observed. These results show that it is possible to apply the lattice Boltzmann method to practical analysis of fluid motions with the compressibility.