The invention relates to a device and method for testing an imbibition expansion rate of imbibition resin particles. The device provided by the invention comprises a bracket (1) with a base and a regulating valve (9), an imbibition testing container (2) detachably arranged on the base of the bracket (1) and used for containing the imbibition resin particles and an absorption liquid to be tested, a testing rod (5), a magnetic ring (4) sleeved on the testing rod (5) in a slidable manner, a screen (3) arranged under the magnetic ring (4) and integrated with the magnetic ring (4) into a whole, a sensor (6) one end of which is fixed on the bracket (1) through the regulating valve (9) and the other end of which is connected with the measuring rod (5), a converter (7) connected to the sensor (6), and an acquisition system (8) connected to the converter (7). The device and method provided by the invention are capable of accurately and effectively measuring the imbibition expansion rate of the imbibition resin particles, and the device is convenient to operate and good in repeatability.