In order to solve the problem that the safety separation distance of the minor-caliber fuze of our country is too short.The pseudofluids technology was introduced to design the delay arming of fuze about ball rotor with variable rotary moment.The principle of ball rotor with variable rotary moment was analyzed by the expression of rotary torque deduced from Euler equation.The dynamic simulation of certain delay arming of fuze about ball rotor with variable rotary moment was completed by using the software of ADAMS.The results showed that the initial rotating time of ball rotor was regulated by the flow of pseudofluids through an orifice of ball rotor so as to make the small caliber fuse attain required safety separation distance.