Abstract: The laws, tensile strength decreases gradually with the increase of hight-to-diameter ratio and the change curve can be better simulated with a cubic function, have been found through splitting tensile test on a large number of disc specimens with different hight-to-diameter ratios. However, as the Brazil splitting tensile strength is based on the assumption of plane in elastic mechanics, there are great differences between the calculated results and the actual three-dimensional experimental results, and it also brings trouble to the research on the dimensional effect. The stress distribution rules of disc specimens with different hight-to-diameter ratios through FLAC^3D shows that the more close to the ends, the higher of the horizontal stress; the larger of the hight-to-diameter ratio is, the higher of the horizontal stress of the central point of the specimens; the first fracture starting point is at the center of the ends rather than at the internal center point. Based on which test results of Brazil split can be revised to get a more real dimensional effect of the tensile strength.