Abstract: In multi pursuit-evasion games the capability of pursuers and evaders is unequal, especially in the maximal velocity capability. Whether can the pursuers in low maximal velocity capture the evader in high maximal velocity? The success capture condition of unequal robot in multi pursuit-evasion games includes n pursuers and single evader is researched. If every robot’s vision field of pursuer is infinite, the pursuers can always capture the evader even if the top velocity of the pursuers is lower than the evader when the two necessary conditions are satisfied simultaneity with appropriate strategy. (1) The velocity ratio of the pursuer and evader is higher than the value of sin (π/n) and (2) Position of the evader should be located in the convex polygon which is composed by the position of the multi pursuers and the adjacent Apollonius circles formed by the evader and each pursuer should be intersected or tangent. If the two necessary conditions are not satisfied, the pursuers may capture the evader sometimes but not necessarily. The optimal strategy of the pursuer and evader is designed in success capture conditions. The experiments can also prove that success capture conditions are correct.