In order to study the uniaxial compression mechanical characteristics of limestone under high temperature treatment, the physical characteristics test, uniaxial compression test, SEM electron microscope scanning and XRD diffraction analysis were carried out on limestone treated at room temperature (25 ℃) and high temperature (100 ℃, 200 ℃, 300 ℃, 400 ℃, 500 ℃ and 600 ℃). Based on the micro-fracture law of rock, the mechanical characteristics of limestone under uniaxial compression were analyzed. The results show that with the increase of treatment temperature, the apparent color of limestone changes from gray to reddish brown, and the volume growth rate and mass loss rate increase nonlinearly. High temperature treatment makes limestone micro-texture stratification, fracture development, pore dissolution, and the fluctuation and sharp angle characteristics of compression fracture surface are significant. High temperature catalyzes the pyrolysis and chemical reaction of limestone mineral components, and there is a significant linear correlation between the comprehensive hardness coefficient and the firmness coefficient of rock. It is revealed that the threshold temperature of thermal damage of limestone is 200 ℃, and the peak strength and elastic modulus reach the peak at this temperature.