A printer with replaceable modules has a printer and an electronic expansion device. The printer has an operating panel mounted on a top thereof, a connecting mechanism formed on a bottom thereof, and at least one connector mounted on the bottom thereof. The electronic expansion device has a mating connecting mechanism removably assembled on the bottom of the printer, and a mating connector connecting with the connector on the bottom of the printer. The printer has an identification interface electrically connecting with the connector for identifying the electronic expansion device. The electronic expansion device can be a scanner, an entertainment device, a data-access device, or a battery.