The embodiment of the invention provides a network management method and system. The method is applied to a server system comprising a network monitoring module, and the method comprises the following steps: obtaining flow sampling information on data links in a network by using the network monitoring module; judging whether the flows of the data links exceed a flow threshold based on the flow sampling information, and when it is judged that the flow of the first data link exceeds the flow threshold, executing a congestion prevention program on the first data link, wherein the executing the congestion prevention program on the first data link comprises: obtaining flows occupied by data packets transmitted on the first data link based on the flow sampling information of the first data link and sending end information of sending the data packets; and limiting the sending end having the data packet with the maximum occupied flow from transmitting data.