The paper discussed a comprehensive numerical simulation and field work by the usage of waterjet slotting technique to prevent the occurrence of outbursts in soft and outburst prone coal seams.This was based on the geological and geomechanical conditions of Jinjiachong Colliery,Guizhou Province,associated with varied waterjet slotting parameters such as slotting penetration,slotting thickness and slotting distance along the length of borehole.Also,to understand the variation of intal stress of coal seams after waterjet slotting application,the intal stress levels were compared with and without slotting application,and the results indicate that the intal effective stress levels can be reduced to 70％ and 45％ for the vertical and horizontal stresses,respectively,and the gas concentration can be increased up to 5 times when the waterjet slotting is applied.