The invention discloses a device for determining the exchange capacity of hydrogenous strong-acid ion exchange resin. The device consists of a device B and a device C, wherein the device B is an open container, the device C comprises a filter, a flow control device is arranged on the outlet pipe of the device C, and an opening of the device B is connected with the inlet end of the device C. When the flow control device is closed, an airtight cavity is formed between the device C and the device B, and the volume of the cavity is kept invariable. The device C is provided with a ventilation pipe, the bottom end of the ventilation pipe extends into the device B, the top end of the ventilation pipe extends out of the device B, and a gas flow control device is arranged at the top end of the ventilation pipe. In a static state, the bottom end of the ventilation pipe is located above the reaction liquid level. The problem that the resin is sucked into a transfer pipette when the transfer pipette is moved out of a soak solution, accordingly determination of the exchange capacity of the hydrogenous strong-acid ion exchange resin is influenced and a bottle stopper breaks during a test is solved.