A method applied to T.38 gateway for making high-speed facsimile fall back to ordinary facsimile, including: detecting a call menu signal from a calling high-speed facsimile machine; intercepting the call menu signal when the call menu signal containing high-speed facsimile service information is detected; detecting a digital identification signal from a called high-speed facsimile machine; setting V.8BIT in the digital identification signal to zero. The method of the invention is a reliable and effective method for identifying a facsimile service and making a high-speed facsimile process fall back to an ordinary facsimile process.