Abstract: Taking the standard red sandstone samples as research objects，both the self-designed shear creep experimental device of coal or weak rock and the monitor software of coal or rock micromechanics properties were used to make the systematic studies on shear creep properties of red sandstone under different load levels.The phenomena and mechanisms of slope stability occurrence are trial to be revealed based on the conclusions from experiments.The results show：load levels have a significant effect on the shear creep mechanical properties of red sandstone，which will mainly determine the presence of accelerated shear creep stage or not， the destruction of the sample or not and the affect extent of creep test time on mechanical properties.There are two special shear creep stress，τ₁、τ₂,which divides the shear creep of sandstone into three types，certainly not fracture，uncertainly fracture and certainly fracture.The formation process of damage area of red sandstone was showed as a progressive type，and the damage process was showed as a progressive type combined with burst type.There is crack-rich area near the fracture surface，and the fracture surface is not flat shear plane in structure.Shear creep properties of red sandstone under different load may be used to reveal the phenomena and mechanisms of slope stability occurrence.It is considered that rock shear creep of potential slip area in slope is the physical mechanism of slope instability.

Key words: Red sandstone, Shear creep, Potential slip area, Slope, Progressive