In this paper, a similarity measurement formula based on Vague Set is proposed, and is used in selecting the evaluation index system, establishing the preferred vague sets. The candidate data sets in a interval is abstracted into low dimension values. Then, the optimized solution sets is calculated through obtaining the vague similarity measurements between candidate vague sets and the ideal optimal vague set. The similarity measurements between vague set is the core of such application. The simulation results reveal that using the vague optimal method in soft base selection is promising.