The invention provides a method, device and system for measuring available bandwidth of a link, relates to the field of communication technology, and is used for solving a problem of error judgment proneness when a prior art based method is adopted for judging bandwidth of the link. The method includes that a device (10) determines a measurement method, shared with a device (20), for measuring theavailable bandwidth of a first link; packages information indicative of the measurement method and sending parameter information of a measurement message prescribed by the measurement method into a first message, and sends the first message to the second device (20) through the first link and determines a measurement message sending rule; and sends at least one measurement message to the device (20) via the first link according to the measurement message sending rule. The technical scheme eliminates influence from other links, so that accuracy of available bandwidth measurement of the first link is improved.