Quartz and calcite grains in fault gouge at the Shenxigou section of Wenchuan earthquake fault zone were investigated by micro-Raman spectroscopic measurement. All the peaks shift towards high-frequency due to the tectonic stress during fault slipping. The 464 cm-1 peak arising from the micro-fractured quartz grains coexisting with clay minerals such as chlorite shifts by 2.50 cm-1, while the 464 cm-1 peak arising from the weakly fractured and pure quartz grains shifts by 3.78 cm-1. This likely resulted from that the microfissure filling in loose clay minerals increases the surface area of the quartz grains, in which the stress existing in the crystal lattice was accelerated to be released. The 1 085 cm-1 peak arising from calcite grains shifts by 2.70 cm-1 towards high-frequency, as a result of the Wenchuan Ms 8.0 earthquake. The compressive stress in the fault plane was estimated to be at least 496 MPa during the fault slipping when the big earthquake happened according to the Raman peak frequency shift of calcite grains and the available experimental data. The results showed that the Raman spectra of minerals within fault zone should provide information of mechanisms on the fault plane when fault slipping takes place.