Aim\ To search for a new way to improve is adopted the performance of delay arming of fuzes. Methods\ The structure of variable moment of inertia is adopted. The ball rotor is filled with fine pellets

which can flow out under centrifugal force. With continuous flow of the pellets

three main moments of inertia are changed. It brings an additional delay. By this way a long delay arming time of fuze can be got. Results and Conclusion\ The theoretical analysis and simulation confirm the validity correctness moment of this design.