The invention belongs to the technical field of metal cutting tool processing, and more particularly relates to a processing method of screw rotor hob tooth form. The existing processing of the screw rotor hob has two major drawbacks: 1. the tooth form of the hob has low accuracy and the roughness of the tooth form cannot meet requirements; and 2. operating personnel are required to be experienced, and the production efficiency of the hob is low, thus being not suitable for batch production. The processing method of the screw rotor hob comprises the following processing steps of: 1) manufacturing a rough sample plate, a fine sample plate and a comparison plate according to a tooth form curve of the hob; 2) manufacturing a rough perching knife and a fine perching knife by sample plate testing; 3) roughly perching the tooth form of the hob by the rough perching knife, and then carrying out heat treatment; 4) fine turning the external contour of a rolling wheel by the fine perching knife;5) rolling a formed grinding wheel by the rolling wheel; and 6) relief grinding the tooth form of the hob by using the rolled formed grinding wheel. The processing method has small relief grinding allowance and high precision of the tooth form, and can effectively improve the production efficiency of the hob.