The invention provides a capacity matching method and device. The capacity matching method is applied to a battery pack; the battery pack comprises a plurality of battery modules; each battery module comprises a plurality of serially connected battery cell groups; the method comprises: discharging the battery pack until the battery pack reaches single-pack protection voltage, and determining the battery modules with abnormal voltage in the battery pack as abnormal modules; carrying out full charging and full discharging tests on the abnormal modules and judging whether the abnormal modules need to be replaced or not according to testing results; if not, carrying out capacity matching on the abnormal modules and normal modules. By adopting the capacity matching method and device, provided by the embodiment of the invention, the problem that the capacity of the battery pack is not matched can be effectively solved and the service life of the battery pack is prolonged.