The invention discloses an online fault location method and equipment of a radio frequency transmission line, wherein the online fault location method of the radio frequency transmission line includes that an online test is conducted on the tested radio frequency transmission line at a single end of the radio frequency transmission line, namely, on the premise of not influencing normal working of the line, an interposer is connected with one end of the tested radio frequency transmission line, a high-precision linear frequency modulation signal source which is controlled by a control unit of a fault location main machine produces linear frequency modulation frequency signals, and the frequencies of the linear frequency modulation frequency signals are close to communication working frequencies. A scanning test on the tested radio frequency transmission line is started through the interposer in a method of online. The scanning test is conducted from one end of the tested radio transmission line to the other end of the tested radio transmission line, the one end of the tested radio frequency transmission line is close to the interposer and the other end of the tested radio transmission line is further away from the interposer. Return losses and standing waving values of each position and corresponding positions in the tested radio frequency transmission line, an interface, a wire jumper, a phase adjusting head, a lightning arrester, a direct current separator or all the transmission line of an antenna are tested, and the interface, the wire jumper, the phase adjusting head, the lightning arrester, the direct current separator and the antenna are connected with the tested radio frequency transmission line. And a specific position of a fault in the tested radio frequency transmission line is displayed.