通过对砂岩进行加温三轴试验，分析了超声波速度与应力的关系。根据实验结果，提出了一种以横波速度最大值评价砂岩试件微裂纹开始产生时的应力值的方法，即横波速度峰值点及其后波速减小现象说明载荷下的砂岩产生了新的微裂纹。Ｓ波速度峰值点的应力值大小，随砂岩的孔隙度和粘土含量的不同而不同。致密砂岩是大于破裂强度的５５％ 出现Ｓ波速度峰值，而疏松砂岩在大于破裂强度的７０％ 才出现Ｓ波速度峰值 Through the triaxial test of heating sandstone, the relationship between ultrasonic velocity and stress was analyzed. Based on the experimental results, a method was proposed to evaluate the stress value at the onset of microcracks in the sandstone specimen at the maximum of the shear wave velocity. That is, the phenomenon of the peak value of the shear wave velocity and the decrease of the post-wave velocity shows that the sandstone under the load has produced new micro crack. The magnitude of the stress at the peak S-wave velocity varies with the porosity and clay content of the sandstone. In tight sandstone, the S-wave velocity peak appears more than 55% of the rupture strength, whereas the S-wave velocity peak appears in the unconsolidated sandstone at more than 70% of the rupture strength