The invention relates to the technical field of electronic product machining, in particular to a glass piece four-side polishing production line. The glass piece four-side polishing production line comprises a first polishing mechanism and a second polishing mechanism, the first polishing mechanism and the second polishing mechanism each comprise a lower conveying belt, the glass piece four-side polishing production line further comprises a positioning assembly, the positioning assembly comprises a positioning plate used for clamping a glass piece and a movable plate, the positioning plate andthe movable plate are relatively arranged, the sides, close to the lower conveying belt, of the positioning plate and the movable plate are parallel to the lower conveying belt, a plurality of guiderollers are rotationally arranged on the sides, close to the lower conveying belt, of the positioning plate and the movable plate, and the roller faces of the guide rollers protrude out of the side face of the positioning plate or the movable plate, the guide rollers on the positioning plate is aligned with a polishing piece on the same side of the positioning plate in the conveying direction of the conveying belt; ad the movable plate is slidably arranged and connected with an air cylinder used for driving the movable plate to move towards the conveying belt. According to the glass piece four-side polishing production line, the problems that in the prior art, a feeding mechanism cannot be suitable for conveying of glass of different sizes, and the glass is prone to being damaged in the positioning process can be solved.