The invention discloses a test and detection apparatus for an ion exchange resin of a direct-current power transmission valve cooling system. The apparatus comprises a main circulation loop and a deionization branch, wherein the main circulation loop comprises a main circulating pump, a first water-water heat exchanger, a water chilling unit and a simulated load pipeline system, the deionization branch comprises a flow control valve, a flow transmitter, an ion tank and a voltage stabilization system, and the deionization branch joins with the main circulation loop at an inlet of the main circulating pump. The apparatus can test exchange performance of the resin under the condition of different quantities of flow in the deionization branch so as to determine whether the exchange performance of the resin meets requirements and to select an appropriate quantity of branch flow. Moreover, the apparatus can test exchange performance of the resin under the conditions of different cooling medium temperatures and different voltage stabilization modes so as to provide bases for selection of an appropriate operating temperature and an appropriate voltage stabilization mode. The apparatus can also detect and test water distribution components in a converter valve, e.g., PVDF pipes, FEP pipes, aluminum radiators, electrodes or the like.