The invention discloses a precise processing device for sewing. The device comprises a rack, the rack is provided with a worktable surface, the worktable surface is provided with a sliding rail, the sliding rail is provided with a sewing machine seat, the sewing machine seat is provided with a sewing machine, and the front end of the sewing machine is provided with an optical fiber transmitter; the worktable surface is provided with a sliding table, a sewing mold is clamped to the sliding table and comprises a bottom plate and a pressing plate which are hinged to each other, the bottom plate is provided with an origin sensor, the pressing plate is provided with a through hole, and the through hole is internally provided with a cover plate. Cloth is placed on the bottom plate, the pressingplate and the bottom plate cooperate with each other to realize clamping and loading, the through hole is filled with cloth parts, and the cover plate is adopted for pressing; the sewing machine seatdrives the sewing machine to move back and forth along a guide rail, the sliding table drives the sewing mold to move left and right, and an origin locator and an optical fiber generator ensure that the sewing machine performs sewing work in a gap between the cover plate and the through hole. The working intensity is low, manual driving of the cloth for rotation and sewing is not needed, only thecloth needs to be clamped, the sewing effect is good, and the production efficiency is high.