A detection apparatus and method for an ion migration spectrum include acquiring an ion migration spectrum of pure carrier gas and an ion migration spectrum of carrier gas containing a test substance sample and performing differential process on the ion migration spectrum of the pure carrier gas and the ion migration spectrum of the carrier gas containing the test substance sample to acquire a differential spectrum. The value of a characteristic peak of the differential spectrum represents properties of the sample of substances. The method avoids interferences on the migration spectrum from interference sources of the apparatus itself, thereby improving detection sensitivity and accuracy of the ion migration spectrum, and migration spectrum shift caused by variations in the environmental conditions can be found and corrected through the differential process on the migration spectrum of the pure carrier gas, thereby achieving self-stableness and self-correction of the ion migration spectrometer.