A process for cleaning a compound semiconductor wafer; the compound semiconductor wafer comprises, taking gallium arsenide (GaAs) as a representative, a group III-V compound semiconductor wafer. The process comprises the following steps: 1) treating the wafer with a mixture of dilute ammonia, hydrogen peroxide and water at a temperature not higher than 20° C.; 2) washing the wafer with deionized water; 3) treating the wafer with an oxidant; 4) washing the wafer with deionized water; 5) treating the wafer with a dilute acid solution or a dilute alkali solution; 6) washing the wafer with deionized water; and 7) drying the resulting wafer. The process can improve the cleanliness, micro-roughness and uniformity of the wafer surface.