According to explosion mechanics and fracture mechanics，the initiation mechanism of the crack and its expansion of orientation fracture blasting were studied，the mechanism of crack initiation and its expansion of orientation fracture blasting by linear cumulative cutting charge in rock were studied，then the linear cumulative cutting charge was designed and tested in laboratory and field. The directional expansion of crack is satisfactory from the experiment and the result of field test is very good,the ruggedness fracture plane is less than 55 mm and the rates of half－hole marks are 100%.