The invention discloses an apparatus and method for determining strength of particulate activated carbon for water treatment, the apparatus comprises a gas source system for simulating a water treatment process, a gas distribution chamber, a carbon chamber and a protective chamber; the apparatus has the advantages of good simplicity, good operation simplicity, small errors and the like; the method uses a mixed flow of high-speed air flow and water to flush the granulate activated carbon so as to simulate water flow and air flow flushing the activated carbon and mutual friction of activated carbon granules in the water treatment process, and uses a granule counter to determine the amount of fine granules in water after the ending so as to characterize strength of the activated carbon for water treatment. Compared with existing ball milling method, the method provided herein is more capable of reflecting the truth of the water treatment process of the activated carbon, with determination results better matching with the practical truth.