The invention discloses a mechanical precut slot blasting mining method of slightly inclined thin jade ores. The method specifically comprises the steps that a stope is arranged along the moving direction of the ores, ore pillars are recovered first, then a room is recovered, ore pillar recovery is performed by using a level haulageway (8) and a transportation mountain roadway (9) as initial free surfaces, artificial ore pillars are formed by reinforced concrete after the ore pillar recovery is completed, and the artificial ore pillars are reinforced concrete pillars (7) for replacing the ore pillars; the recovery is pushed to both sides in the room along the moving direction and the inclined direction of the ores, and the following type filling is performed in the rear; the precut slot blasting method is adopted for exploitation, a protective layer is reserved on a base plate of the room, a precut slot (15) is mechanically cut by a saw, a rock layer between the precut slot and the ores is used as the protective layer (14), and millisecond blasting is performed on surrounding rocks on the upper part of the protective layer; the protective layer is manually or mechanically split and stripped, and the ores are cut by a hand-push type cutting machine for ore removal. The mechanical precut slot blasting mining method has the advantage of high efficiency in production, the recovery rate reaches up to 95%, and the cost for transporting and treating barren rocks is reduced.