In situ surface Raman spectroscopy has been extended to study silicon electrode surfaces by optimizing the Raman system and the surface roughening method. The time-dependent etching processes were monitored in a dilute HF aqueous solution and the initial oxidation processes of the hydrogen-terminated surface in different pHs were studied at the open circuit potential. The results indicate that the silicon surface could be overwhelmingly terminated with hydrogen rather than fluorine in the HF-based solution. The smoothening effect of OH- on the silicon surface is through the attack of the = SiH2 site. It demonstrates that Raman spectroscopy is a powerful in situ technique for investigating the etching process of silicon surface.