The application proposes a method for etching a III-V-group semiconductor material. The method comprises: an III-V-group semiconductor material in an etching cavity is etched by using etching mixed gas on a preset condition, wherein the etching mixed gas includes methane, hydrogen, argon and chlorine-based gas; and the volume ratio of all gas in the etching mixed gas is as follows: methane: hydrogen: argon: chlorine gas = 1: 3: 1: 1 to 1: 3: 2: 3. With the etching method, deep etching with the etching dept of 10 microns is carried out on the III-V-group semiconductor material in an environment at a temperature of 50 DEG C.