The utility model discloses a quantitative charging device for crystallization of potassium borohydride. The quantitative charging device comprises a crystallization kettle (3) and is characterized in that a NaBH4 flow sensor (1) and a KOH flow sensor (2) are arranged above the crystallization kettle (3), and the flow sensors are in a closed loop formed by electromagnetic flow meters and electromagnetic valves, and are capable of automatically controlling charging amounts of NaBH4 and KOH. According to the quantitative charging device, the problem of quantitative charging of the crystallization of the potassium borohydride is well solved, and the production cost is saved.