The present invention provides a Set-Top Box, a home gateway, and a method and a system for implementing interaction between the Set-Top Box and the home gateway, and the method comprises: the Set-Top Box transmitting a subscription message to the home gateway by means of a UPnP protocol message; the home gateway receiving and parsing the subscription message, combining a subscription response event according to the parsed subscription information, and then transmitting the subscription response event to the Set-Top Box by means of a UPnP protocol message; and the Set-Top Box triggering a corresponding operation according to a subscription response event message, after receiving the subscription response event message. The flexible coordination between the home gateway and the Set-Top Box can be implemented in accordance with the present invention, which can achieve the purposes of automatic diagnosis and automatic adjustment of services, and improve the user experience effectively.