To solve the problem about time-sharing controlling of ammunition parts manufacturing, design the precision indexing mechanism model of ammunition part manufacturing. Based on motion principle between contour surface of driving wheel and roller of driven wheel, both transmission model and contact equation were established between driving wheel and driven wheel. According to mathematical relationships for velocity direction located in contact point between driving and driven wheel, the parametric relationship between driving and driven wheel was deduced. The parametric design module of Creo software was employed to construct parametric design model of the higher precision indexing cam mechanism. The availability of design model was verified by design example. The results show that research has reference valuable for both ammunition rotary machining and charge ammunition manufacturing.