The invention relates to a small-sized chassis type battery swap station, and especially relates to an expandable small-sized chassis type battery swap station applying a lifter, which resolves the problems of the conventional battery swap station that automation degree is not high, occupation area is quite large, and scale cannot be expanded. The battery swap station comprises a charging container and a power-changing container, arranged in parallel, and a RGV charging trolley disposed on a first transverse moving guide rail, stretching across the two containers. The power-changing containeris provided with a vehicle access channel, and the power-changing container is provided with a charging battery rack and a lifter. The charging battery rack is provided with a plurality battery placing cases, each of which is provided with a first battery conveying device, two side spacing devices, a positioning fender, and a charging device. A lifting object-carrying table is provided with a second battery conveying device, and the lower part of the lifter is provided with a translation drive mechanism. The power-changing container is provided with a four-column lifter. The RGV charging trolley comprises a body base, an object-carrying panel, a lifting mechanism, a third battery conveying device, a battery unlocking and locking mechanism, and a transverse walking mechanism.