The utility model discloses an accurate processing three -jaw ring flange positioning fixture for centre bore, the positioning fixture includes anchor clamps body, work piece splint subassembly, kicking block splint subassembly and T shape kicking block, work piece splint subassembly and kicking block splint subassembly are all fixed and are set up on the anchor clamps body by punch holder and lower plate constitution, the lower plate of work piece splint subassembly and kicking block splint subassembly, and the punch holder of work piece splint subassembly and kicking block splint subassembly all slides and sets up on the anchor clamps body, and just two punch holders are connected with respectively and drive its pneumatic cylinder that reciprocates, T shape kicking block carries out the neck pipe of centre gripping and is used for the roof of the tight three -jaw ring flange in top, the perpendicular one end that sets up at the neck pipe of roof including the kicking block splint subassembly of being convenient for. This novel operation process is simple, reasonable in design, and double splint group sets up can coil the work piece by accurate mounting flange, and the joining of T shape kicking block can make the work piece neat not inclined to one side, and the centre bore of processing is accurate unanimous, effectively improves the product precision.