The invention belongs to the technical field of voltage and insulation, and particularly relates to a composite insulator aging state evaluation method based on hygroscopicity and a dielectric property. A piece of umbrella skirt of a high voltage end of a composite insulator to be tested is cut, a silicone rubber material of a surface layer of the umbrella skirt is taken to be made into a circular sheet sample with a diameter of 3cm and thickness of 0.7+/-0.1mm, after the sample is subjected to surface treatment and is dried, a dielectric loss test in a moisture absorption process with humidity of 80% is carried out, a saturated dielectric loss factor is determined, and a sample aging score is obtained according to the saturated dielectric loss factor and a scoring formula S=56.41+56.58e-12.35*tan[delta], thereby judging the aging degree of the composite insulator. By implementation of the composite insulator aging state evaluation method, the aging degree of the silicon rubber material of the composite insulator can be judged accurately and sensitively, and the aging states of samples of different areas can be scored in a unified manner, thereby providing suggestions for reference for formulation of a maintenance schedule of an operation department.