Abstract: Influenced by multi-tectonic movement, rock mass on Heihe reservoir area is deeply fragmentized and with different level of weathering. It is critical to analysis rheologic properties of strong weathered and weak rock mass for keeping the reservoir running safely after impoundment. But, under the lower field stress level there, weak rock mass in faults area may demonstrate different rheologic features from intact rock mass inevitably. Weak rock mass and intact rock mass should be treated as two different materials when the rheology is taken into account to build models. Based on this, rheologic models under different field stress for rock-mass are put forward for the dam area after detailed analysis.