The behaviors of dust explosion of flake aluminum powder,RDX powder and their mixtures were studied experimentally by using a 20 L explosion vessel. On the basis of the maximum explosion pressure and the maximum pressure rise rate,it has been demonstrated that there exists a synergistic effect on the maximum explosion pressure in the mixtures of the two powders with proper ratios. In addition,the history of the maximum explosion pressure rise rate is changed with the variation of aluminum powder contents of the mixtures.