There are many types of tidal current power generation devices, and it is necessary to make comprehensive evaluation of tidal current power generation devices in order to provide valuable reference for the improvement of their performance indexes. On the basis of the analysis of the tidal current power generation device performance indexes, the hierarchical model for comprehensive evaluation of device performance is given in this paper. By normalizing the membership matrix elements based on fuzzy comprehensive evaluation model, all the values of the matrix elements are restrained in the range of 0.0 to 1.0, hence the complexity of the calculations is reduced. Vector similarity is used to determine the expert weights which reflect the knowledge and experience of the experts. This paper presents an improved method for rank correlation analysis, and calculates the comprehensive weight value and the final evaluation results of tidal current power generation devices. The presented method improves the credibility of the evaluation. In the end, measured data of two units of tidal current power generation devices are evaluated in the paper, and the effectiveness of the presented method is verified.