Geological investigation revealed that one of the most serious geological threats to rock art in Helan Valley was unstable rocks. The unstable rocks surrounding the rock art in Helan Valley are classified as three types: falling, sliding and toppling, depending on their potential modes of movement. The physical properties of the rocks, such as mineral composition, density, porosity, water absorption ability and uniaxial compressive strength were obtained through laboratory experiments. In addition, the parameters of the rock mass strength and the controlling stractural planes (e. g., uniaxial tensile and compressive strength, deformation modulus, internal friction angle and cohesion) in the Helan Valley were estimated, respectively , by the Hoek - Brown criterion , the linking ratio method and the rock surface rebound values . The stability analysis was performed using different unstable models . The results indicated that some of the rocks are unstable and need to be reinforced.