Urban areas are regional economic, political, and cultural centers, and the role of urban area determines its significance in tourism research. Applying urban network analysis, this study examined the role of subway in urban tourism traffic and its optimization in the context of individual tourists in the Nanjing’s main urban districts. The main findings are as followings. (1) Subway plays a greater role in the short-distance “do it yourself”(DIY) tours; (2) The distribution of subway lines and stations can meet the needs of DIY tourists in the central urban area, but is hard to satisfy the needs in peripheral urban areas; (3) The lines and stations of greater gravity are concentrated in the old town, which has high population density and rich tourist attractions; those of greater betweenness are situated near the boundary between Pukou District and Luhe District; those of greater closeness are located in the bordering area of the three main districts—Gulou, Xuanwu, and Qinhuai; stations with greater redundancy are mainly located along the subway lines with higher sinuosity in transitional urban areas; (4) The gravity, closeness, and redundancy values of transit stations are higher than those of general stations, but some general stations have higher betweenness values. The suggestions are as follows. (1) Bus lines should be opened for tourist attractions exclusively within the peripheral urban areas. (2) During the tourist rush reason, special subway trains should be operated for tourist attractions. (3) Make full use of bus diversion function and combine the usage of trunk roads in order to avoid redundant lines, and cut the journey. (4) Upgrade some general stations to transit stations in order to reduce the pressure of crowded lines.