The invention discloses a method for evaluating the damage degree of a drilling fluid based on the characteristics of high temperature and high pressure gas reservoir, and belongs to the engineering field of oil and gas drilling fluids. Compared with the original industrial standard SY/T6450-2002, the invention is different in the following aspects: the core displacement medium is changed from kerosene to gas; a holder for measuring core permeability is designed from a normal temperature type to a high temperature and high pressure type; the drilling fluid is changed from new pulp into on-sitepulp; the core pollution process changes from a single dynamic pollution to a double pollution of dynamic pollution and static pollution; and the pressure loading mode of the displacement medium changes from a constant flow velocity to a constant pressure. Compared with the original industrial standard, the evaluation method is more suitable for high temperature and high pressure gas reservoirs and is more consistent with the actual drilling fluid pollution reservoir process, and the evaluation results are more realistic and reasonable.