Injection pressure applied in geological Carbon dioxide (CO2) storage must exceed the existing pore pressure in the reservoir rock to sequestrate supercritical CO2 underground. However, high injection pressure generates new fractures or reactivates existing faults in the rock mass, triggering seismic activities. Therefore, the maximum allowable injection pressure of the reservoir rock must be assessed as an essential parameter to secure the injection of CO2 before proceeding geological CO2 storage. In this study, the failure criteria of the saturated Yutengping Sandstone, which is a reservoir rock at Tiehchenshan, were investigated by consolidated drained triaxial compression tests. Then, the Mohr circles of in-situ stresses under different coefficients of critical friction of fault and various depth could be drawn. Maximum allowable injection pressure of reservoir layer was obtained through the relationship between Mohr circles and failure criteria. Among which, failure criterion for peak strength could be used in evaluating the generation of new fractures in intact rocks; and failure criterion for residual strength could be used in assessing the injection pressure causing slip on existing faults. Therefore, this assessment method is applicable in the preliminary analysis on the suitability and safety of a geological CO2 storage site.