Basic mechanical properties of Tibetan rubble stone masonry, a unique architectural structure in western China, may affect the bearing capacity of architectural structures. In this study, a compression test was carried out on a Tibetan rubble prism to investigate its failure mechanism and stress-strain characteristics under uniaxial compression. Based on the experimental results, we obtained two simple compression constitutive models for Tibetan rubble stone masonry, established equations applicable to predicting the compressive strength of Tibetan rubble stone masonry, and obtained a relationship between compressive strength and the elasticity modulus through a regression analysis.