In this paper the characteristics of IR spectra, Raman spectra and EPR spectra of cassiterites from Yunlong are studied and their geological significances are discussed. According to the spectral shape, absorption strength and frequency, the IR spectra of Yunlong cassiterites might be divided into two types, i. e., type A and type B. The spectra of type A have the same characteristics as the spectra of cassiterites from Nb-, Ta-bearing pegmatite type and granite type tin deposits, whereas the spectra of type B are identical with those of cassiterites from hydrothermal tin deposits in features. Combined with macroscopic geological investigations, it is found that the IR spectra of cassiterites formed in oxidic stage belong to type A and those of cassiterites formed in sulfidic stage belong to type B. A study on IR spectra of the cassiterites indicates that these two ore-forming stages are characterized by different metallogenic mechanisms and processes. The metallogenic process of oxide stage and that of sulfide stage are similar to the ore-forming process of magmatic deposits and that of hydrothermal tin deposits respectively. The symmetries of the spectral shape and vibration frequencies of Raman spectra vary considerably with the changes of cassiterites in composition and structure, suggesting the difference in formation condition of cassiterites. In the EPR spectra of Yunlong cassiterites the g factore of V(4+) spectrum are =1.9265, g=1.9184, and the constants of superfine structure are A=38.17 (10(-4)cm(-1))and A=124.88(10(-4)cm(-1)). The researches on stability field of V(4+) show that the Yunlong cassiterites were mainly formed in relatively alkaline and somewhat reducing environment.