The invention discloses a multi-screen interaction method and system based on a WiFi AP, wherein the method comprises the following steps that: a Sink registers information including a MAC, a service identification code and service description in a cloud server; a Source is connected to the cloud server, and inquires and obtains the information including the service description and the service identification code from the cloud server according to the MAC; and the Source sends the service identification code, an instruction and data to the cloud server, and pushes the instruction and the data to the Sink through the cloud server. The method disclosed by the invention comprises the processes, such as service registration, service discovery and content pushing; service discovery in local network connection is unnecessary to exist between the Sink and the Source; namely, the Sink and the Source are unnecessary to connect to the same WiFi AP or be in the same network segment; direct connection between the Sink and the Source is also unnecessary; and service discovery and multi-screen interaction can be completed only in need of connecting the Sink and the Source to a network.