The invention discloses a calibration method of a core-based gas permeability measuring device. The calibration method comprises the following steps of clearing away air in a pipeline by adopting nitrogen; collecting cross section areas and lengths of to-be-measured cores and clamping the to-be-measured cores in a core holder; controlling the inlet pressure of the core holder by adjusting a gas permeability tester, and collecting pressure values and the core outlet flow rate; fitting out the functional relationship by quadratic difference of the core outlet flow rate and the steady inlet and outlet pressure. According to the functional relationship and the Darcy law, the corresponding inlet pressure and the gas-measured permeability are calculated at the utmost pressure, the relation function of the gas-measured permeability and the reciprocal value of the average pressure is created, and the nodal increment of the horizontal segment of the section function is regarded as Kerr permeability. The absolute core permeability can be quickly and accurately obtained by the gas-measured permeability calibration method-a theoretical limit method.