In this study, we conducted a number of mechanical experiments on sandstone samples from Junan County, Linyi City, in order to investigate the mechanical properties of the sandstone samples after being subjected to high temperatures, ranging from 25 ℃ to 850 ℃. We plotted the peak strength and deformation displacement curves of the sandstone samples, based on the results of the uniaxial stress experiments under different temperatures. We observed the changes and differences in the sample microstructures after different temperatures using scanning electron microscope (SEM) technology. The results of the sandstone samples' uniaxial stress tests are as follows: (1) At temperatures between 25 ℃ and 400℃, the peak strength of the sandstone samples appears to fluctuate, but the overall strength changes only slightly. This means that the samples share the same mechanical properties, and the strength of the samples under these temperatures is steady. (2) When the temperature is higher than 400 ℃, the peak strength of the sandstone samples begins to decline rapidly. (3) With increasing temperature, the overall deformation displacement of the sandstone samples increases as well, growing very slowly, but increasingly, when the temperature is higher than 400 ℃. In addition, the SEM images show that the pores and fissures of the sandstone samples sharply increase when temperature reaches 400 ℃. Cement particles in the samples begin to disappear when the temperature reaches 500 ℃. The study shows that the macroscopic mechanical properties of sandstone change radically at high temperatures.