An optical fiber probing system has been designed and manufactured with special consideration for simultaneous measurement of Raman signal and scanning tunneling microscopy (STM) image. In order to improve the collection efficiency of Raman signal, the optical fiber probe carrying one excitation fiber and five collection fibers are surrounded the STM tip to fully make use of the limited space. Moreover, the graded refractive index (GRIN) lens with very short focal length has been used to ensure larger relative aperture. With the aid of this probing system, Raman spectra with good signal-to-noise (S/N) ratio have been obtained, and a combined base of Raman spectroscopy and STM was constructed. The preliminary results have shown that the combined base provides a new method for in-situ and real time studies on solid/gas and solid/liquid interfaces, by which the topography of the solid surfaces and the detailed structural information of adsorbed species can be obtained simultaneously.