The N00 method is a highly efficient and resource saving mining method, witch a key step is to quickly separate the gob roof and the roadway roof by making a slit between them. Based on the water jet theory and technology, a new idea of using abrasive jet directional cutting roof is proposed. The structural composition and working principle of the abrasive jet directional cutting system are studied, and the water jet nozzle, cutting nozzle, orienter, conveyor, abrasive are designed. Through experiment, the working parameters of the abrasive jet directional cutting has been optimized, and the roof cutting test was carried out on the S1201-II working face of a mine in Shaanxi. The results show that under the conditions of jet pressure 25MPa, nozzle diameter 1.5mm, abrasive type yellow sand / quartz sand, abrasive concentration 3.5%, cutting speed 4.4mm / s, the developed system is able to make slits at the same time in 4 holes of 7000-8000mm deep within a cycle time (50min).