In this paper, the structure of titanium-silicon pentasil type molecular sieve which we synthesized is studied with different methods. IR and Laser Raman spectral analyses indicate that the Ti-O-Si vibration occurs in the molecular sieve. It is proved by ESR analyses that Ti4+ is located in environment of distorted tetrahedron. The study on the surface of Ti-Si pentasil type molecular sieve by XPS further verifies that Ti4+ in framework is present in the form of TiO4 tetrahedron. The results of the electron probe micrograph analyses indicate that Ti enters the framework of molecular sieve. X-ray powder diffractometer exactly determined unit cell parameters of Ti-Si pentasil type molecular sieve. The unit cell volume of Ti-Si zeolite increased with increasing the content of titanium which is consistent with the longer Ti-O distance, compared with the Si-O one.