Token bucket packet loss optimization method and system

The invention provides a token bucket packet loss optimization method and system, and relates to the communication technology. The method comprises the following steps: acquiring the current residual token number of a reverse token bucket of a TCP message which is allowed to pass and a window value of the TCP message; and if the window value of the TCP message is greater than the window maximum value of the reverse token bucket, and/or the current residual token number of the reverse token bucket is smaller than half of the volume of the reverse token bucket, the window value of the TCP message is turned down. According to the token bucket packet loss optimization method, a bidirectional QoS token bucket of an IP is associated, when QoS on one side passes through a TCP message, a reverse QoS token bucket is obtained, whether a window value of the TCP message needs to be modified or not is judged by judging the number of remaining tokens of the reverse QoS token bucket, and the size of follow-up sending flow o