The invention relates to an automatic transmission brake friction plate test device comprising an input end and an output end which are arranged oppositely. The output end comprises an output shaft and a brake housing. The output shaft is connected with the bottom of the brake housing through a flange. A piston, a return spring assembly, a return spring assembly stopping ring, a friction plate assembly and a friction plate assembly stopping ring are successively assembled inside the brake housing. The input end comprises an input shaft and a friction plate hub. The friction plate hub is connected with the input shaft through a flange. The outer side of the friction plate hub is provided with an outer spline and a friction plate hub outer side lubricating oil hole on an outer spline gap. The friction plate hub outer side lubricating oil hole communicates with the interior of the friction plate hub. The friction plate hub cooperates with an inner spline of the friction plate assembly viathe outer spline. The automatic transmission brake friction plate test device greatly improves the overall test efficiency while improving a friction plate performance test, and provides strong support for the design improvement of the friction plate and the brake.