The invention relates to a freeform surface lens fixing device which comprises a base, threaded holes, a circular support, a freeform surface lens, an air pump, a solenoid directional valve, a conduit, a T-type connecting rod, suckers, and a ball screw linear slide. The base is symmetrically provided with a plurality of threaded holes. The threaded holes are used for working together with bolts to fix the base. The base is fixed on an optical platform by bolts. The lower end of the circular support is connected with the base by screws, and the upper end of the circular support is arc. The freeform surface lens is placed on the circular support. The air pump and the solenoid directional valve are fixed on the upper end of the base by screws. The solenoid directional valve is connected with the lower end of the conduit. The conduit and the T-type connecting rod are in interference fit. The T-type connecting rod is connected with the ball screw linear slide. The upper ends of the conduit are connected with the suckers. The problem that a freeform surface lens can easily wear away when fixed using the existing device is solved. A function of freeform surface lens fixation with low damage is achieved.