In order to investigate the influence of Kaiser sampling deviation on underground stress measurements, a mechanical model is set up, by fixing the orientations of 0 and 90 degrees, but changing the orientation of 45 degrees. With the real cores of sandstone at great depth, experiments are performed and the results indicate that Kaiser sampling deviation has effects on underground stresses, in quadric relations. When the sampling deviation angle is less than 5 degrees, the effect can be negligible, but great deviation angle has obvious influence that cannot be neglected. The effect changes with different deviation angle of 0 degree. And for irregular core at great depth, the model can be used to evaluate the measurement errors of stresses.