In order to solve the preferable selection problem of offensive mine-laying plans for unmanned platform like unmanned aerial vehicles (UAV) or unmanned underwater vehicles (UUV), propose unmanned offensive mine-laying operation index system. Based on assess of traditional mine-laying operation, use set pair analysis (SPA) method to describe the identity-contrary degree between each plan and ideal plan while using analytic hierarchy process (AHP) and characteristic attribute value to calculate the weight. At last prove the method by means of the simulation results. The result indicates that the elusive should be taken seriously in preferable selection of plans, and the UUV platform is the first choice while proceeding offensive mine-laying operations. The method provides a new thinking to assess and rank of the unmanned offensive mine-laying plans.