The invention provides a system for preparing ammonium bifluoride by utilizing BOE waste liquid, the system not only can avoid environmental pollution caused by directly discharging the BOE waste liquid, but also can recover and prepare an ammonium bifluoride product with high purity, low moisture content, low investment cost and low production cost, and can reduce the discharge of hydrogen fluoride gas. The system comprises a BOE waste liquid storage tank, a first reaction kettle, a filtering device, a second reaction kettle, a triple-effect evaporator, a cooling crystallizer, a continuous centrifuge, a drying device and an ammonium bifluoride storage tank which are connected in sequence, a supernatant outlet of the continuous centrifuge is communicated with an inlet of the triple-effectevaporator, and the triple-effect evaporator and the drying device are connected with the inlet end of a membrane adsorption system, and the outlet end of the membrane adsorption system is communicated with the second reaction kettle.