The catalytic performance of TS-1 zeolite greatly depends on the types of titanium species and their concentrations in the zeolite. Coupled with UV/vis spectroscopy, we present a UV resonance Raman spectroscopic investigation on the evolution of the titanium species during the crystallization of TS-1 zeolite. It is found that a small portion of Ti species leaches from the solid phase into the liquid phase. The "missing" Ti species in addition to the framework Ti species during the assembly process of TS-1 is identified as isolated "TiO6" species, due to the resonance Raman effect excited at 266 nm. The formation mechanisms of framework Ti species in TS-1 and the relation with the isolated "TiO6" species during the synthesis process are clarified. A synthetic strategy was designed to increase the concentration of the framework titanium by a factor of 1.5 for the actual synthesis of TS-1 zeolite.