In the process of the combat effectiveness evaluation of underwater unmanned swarm, there are such situations as the index system being incomplete and the index weight being improper. In order to solve these problems, we combined analytic hierarchy process and OODA decision chain to build an evaluation index system for the combat effectiveness of underwater unmanned clusters, which reflected target detection, computational analysis, intelligent decision making and coordinated strike. It combined subjective weight and objective weight with the thought of game theory, and studied the combat effectiveness of underwater unmanned clusters with TOPSIS method.