As an essential infrastructure of cities, public transit networks have special importance in decreasing traffic congestion and air pollution. metro network is known as the most efficient mode of public transit due to green. Usually, based on evaluation indices, a suitable approach to the development of a metro network is chosen. In this study, the mixed evaluation index is composed of two component that they are shape and service points. The shape point is calculated by utilizing network length, topology characteristics, station density, and average edge length (integer value between zero and ten). Also, annual passenger and passenger per unit length are utilized to calculate the service point (between zero and one). metro network data of 52 cities in the world are collected. Based on the mixed index, the score of Tehran and New York metro network are equal to 4. 390 (rank 29) and 8. 506 (rank 1), respectively. metro networks are classified into three groups based on connectivity and complexity indices with utilizing fuzzy c-means (FCM) clustering method. Results indicated that the Tehran metro network is a relatively developed system. Another classification with fuzzy boundaries based on average line length and total number of stations is accomplished. This classification results in the Tehran metro network is partly a regional accessibility system. Finally, Results of regression models based on the world trend indicate that currently, length and number of stations of the Tehran metro network should be equal to 206. 3 km (31. 1 km deficiency) and 147 (8 stations deficiency), respectively.