From the definition of system performance, a simplified evaluation system for warship system performance was constructed. Based on the  fundamental assumption of group evaluation, the group evaluation weighting making method for warship overall scheme forms and the concept of confidence matrix were proposed. By building the group judgement matrix optimization model, particle swarm optimization (PSO) was used to revise judgement matrix, to assure judgement consistency and group consistency of group judgement matrix; the decision-making method based on improved TOPSIS  for evaluation, and the combination of distance and grey correlation degree in the similarity degree formula was introduced to ensure the consistency of location and curve shape of optimal scheme and ideal scheme, and enhance the comprehensiveness of the decision-making rules. The application example  proved that the decisionmaking method was feasible as a new method for ship overall scheme evaluation.