Abstract: Rock bursts can be controlled and prevented by the artificial cracks in coal seams through structural transformation. To study the weaken law of the tensile properties and energy accumulation or dissipation with artificial fracture in coal,Brazilian tests were performed on coal samples with prefabricated cracks with different lengths and angles. The study suggested that:with the increase of prefabricated crack length and angle,the loaddisplacement curves of coal tend to be gentle with greater decrease in the peak strength and peak strain. The cumulative number of microcracks and the cumulative energy released by coal in the whole process of splitting gradually decrease with the increase of crack length and angle,so do the number of microcracks and the energy released at the moment of failure. The damage violence of the coal samples tends to decrease in both meso and macro scales. There are three typical fracture initiation modes:① The middle of the matrix crack preferentially;② The middle of the matrix and the prefabricated crack tip crack simultaneously;③ Prefabricated crack tips crack preferentially. Four typical failure modes were observed,tensile failure of matrix,airfoil crack failure and tensile failure of cracks and composite failure of matrix tension,airfoil fracture and secondary fractures.