The invention relates to a system of providing live programs across domains, comprising a live data flow supply module, a live data flow receiving module, a relay management module, relay modules, a first and a second relay management interface module; the live data flow supply module is used for supplying live program data flow; the live data flow receiving module is used for receiving live program data flow; the relay management module is used for selecting at least one relay module from the relay modules and sending information of the relay module to the first or the second relay management interface module; the relay modules are used for receiving program data from the live data flow supply module and sending data to the live data flow receiving module; the first relay management interface module is used for sending relay requirements to the relay management module and receiving relay information; the second relay management interface module is used for receiving relay information from the relay management module.