The invention discloses an aging testing method of shield tunnel elastic sealing gasket finished products. A high-temperature aging box is used for experimentally simulating the long-term stress relaxation of a seal gasket; the stress relaxation rate of the seal gasket is calculated according to the contact stress measured by a high-temperature stress meter. The aging testing method comprises the following steps: a fixture clamps the seal gasket to perform a stress relaxation experiment at normal temperature so as to obtain a short-term stress relaxation coefficient; an aging experiment is performed at different temperature points so as to measure the contact stress at the key time point; the stress relaxation data of the seal gasket under the open amount state of each joint are regressed; the long-term stress relaxation rate for reflecting the chemical stress relaxation is calculated; the short-term stress relaxation rate multiplies the long-term stress relaxation rate to reflect the aging degree of the seal gasket. According to the invention, the ageing of the seal gasket is accelerated by the high-temperature aging box, and the stress attenuation rate of the seal gasket at normal temperature can be obtained by numerical value simulation, so that the experiment time is shortened, and the accuracy of the experiment result is also increased. The stress relaxation rate is considered by utilizing the contact stress of the seal gasket, and is relatively accurate and effective.