The invention discloses a method for detecting the sealing performance of a salt cavern, and belongs to the field of engineering technologies. The method comprises the steps of first, injecting saturated brine into a first salt cavern until the first wellhead pressure reaches a first pressure threshold; second, waiting for a first preset time; third, injecting the saturated brine into the first salt cavern when the current first wellhead pressure is lower than the first pressure threshold until the first wellhead pressure reaches the first pressure threshold, determining the current injected amount of the saturated brine to be the leakage amount, and determining the leakage amount to be 0 if the current wellhead pressure is equal to the first pressure threshold; fourth, waiting for a second preset time, and executing the third step; and fifth, when the number of the recorded leakage amounts reaches a preset value, judging whether the first salt cavern has sealing performance or not according to each leakage amount. The method solves a technical problem that it is difficult to realize sealing performance detection for a salt cavern with unknown underground data, and achieves an effect of being capable of performing sealing performance detection on any salt cavern.