A method and a system for converting the service types of the devices connected to a control gateway are provided. The system includes a server, an open platform, a control gateway and devices connected to the control gateway. Wherein, the device possesses device description information and is operated in a first device service type; the control gateway is electrically coupled between the open platform and the device, holds or obtains the device description information of the device and delivers the device description information to the open platform; the server provides a plurality of device service contents. The open platform further according to the device description information obtains the device service content corresponding to the device from the server and registers the device service content in the open platform.