The invention discloses a dynamic data scheduling method in a multi-path transmission control protocol (MPTCP), comprising the following steps: the round-trip time RTT and the round-trip time variation RTTVAR of each path are measured; whether each path is available is judged according to the RTT and RTTVAR, the congested paths are abandoned, and the available paths are retained; the data transmission capacity of each path is estimated; and a data transmission quota is allocated for each path based on the estimated data transmission capacity and the current sending window, and a scheduler allocates transmission data according to the transmission quota. According to the scheme, the essence of a TCP Vegas algorithm is absorbed on the basis of Lowest_RTT, and improvement is made on the basis, which is equivalent to adding a congestion avoidance control function to the scheduler. The method has far-reaching significance to avoiding path congestion and enhancing the overall transmission capacity of the paths.