The invention discloses a shock absorber oil seal, a shock absorber and a gas inflation method of the shock absorber. The shock absorber comprises a piston rod (10) and the oil seal (20) arranged on the piston rod in a sleeving mode; the oil seal comprises a framework (21) and a sealed rubber body (22) which are combined with each other; the sealed rubber body is provided with a main lip (221) and an auxiliary lip (222); an annular cavity (23) is defined by the main lip, the auxiliary lip and the axial surface of the piston rod jointly; and the sealed rubber body is provided with a gas inflation hole (223) and extends to the annular cavity from the outer side of the oil seal. Due to the fact that the sealed rubber body is provided with the gas inflation hole, nitrogen can be injected into the annular cavity through the gas inflation hole when the shock absorber is subjected to gas inflation, the gas pressure inside the annular cavity is gradually increased till the main lip is opened, and the nitrogen enters the inner side of the oil seal. In this way, the axial surface of the piston rod high in precision cannot be damaged in the gas inflation process, accordingly, the gas leakage and oil leakage situations are avoided, and the service life of the shock absorber is prolonged.