Abstract: The cleat system of coal developed well and the experimental results show a strong discreteness when Brazilian test is used for determining the tensile strength of coal, due to the different angles between loading directions with face cleat and butt cleat respectively, it reduces the accurate degree for describing the tensile strength. We supposed that the face cleat and butt cleat are perpendicular to each other, thereupon then the relation between tensile strength of coal and the angle of loading direction and face cleat is deduced and the coal sample failure modes of different splitting angles in Brazilian test are determined. Plenty of experiments are carried out for validating the calculated results and they are in good agreement. The results show that coal samples are not only have splitting failure along with the loading axis, but also have failure by shearing along the face cleat and butt cleat when the loading direction and cleat is on a certain angle due to the existence of cleat in coal. The shearing strength of coal samples along with face cleat is less than the butt cleat, and they are both less than the true tensile strength of splitting along with the loading axis.