This paper deals with a systematic study on titanite from three granites with known extensive tin mineralization (Qitianling, Huashan and Guposhan) and other three granites currently unknown for important tin mineralization(Lianyang, Dadongshan and Jiufeng) . Electron-microprobe results reveal distinct compositions among three types of titanite. Early-magmatic titanite contains trace of tin (generally<1% SnO2) , whereas late-magmatic titanite with 3 to 26%SnO2 can be found in Qitianling, Huashan and Jiufeng. Hydrothermal titanite is typified by high Al and F contents. Comparison of SnO2 contents for titanite from six granites shows that titanite, either magmatic or hydrothermal, from three tin granites (Qitianling, Huashan and Guposhan) is rich in SnO2 with averages>0.4%, revealing their strong tin mineralizing potential; titanite of Lianyang and Dadongshan granites is very poor in SnO2(<0.1%) , consistent with their barren feature.