A congestion control method, comprising: learning , by an application server from a communications device, that a terminal device has handed over from a source cell to a target cell; detecting , by the application server, a round-trip time, RTT, and a bandwidth, BW, wherein the BW is an available bandwidth of a link from the application server to the terminal device; and determining , by the application server based on detection values of the RTT and the BW, whether network congestion occurs on the link from the application server to the terminal device; and determining, by the application server, a minimum RTT and a maximum BW within a first time period after the terminal device has handed over from the source cell to the target cell, wherein the determining , by the application server based on detection values of the RTT and the BW, whether network congestion occurs on the link from the application server to the terminal device comprises: if the minimum RTT is greater than a historical minimum RTT and the maximum BW is less than a historical maximum BW, determining, by the application server, that the network congestion occurs on the link from the application server to the terminal device, wherein the historical minimum RTT is a minimum RTT detected by the application server before the terminal device hands over from the source cell to the target cell, and the historical maximum BW is a maximum BW detected by the application server before the terminal device hands over from the source cell to the target cell. learning , by an application server from a communications device, that a terminal device has handed over from a source cell to a target cell; detecting , by the application server, a round-trip time, RTT, and a bandwidth, BW, wherein the BW is an available bandwidth of a link from the application server to the terminal device; and determining , by the application server based on detection values of the RTT and the BW, whether network congestion occurs on the link from the application server to the terminal device; and determining, by the application server, a minimum RTT and a maximum BW within a first time period after the terminal device has handed over from the source cell to the target cell, wherein the determining , by the application server based on detection values of the RTT and the BW, whether network congestion occurs on the link from the application server to the terminal device comprises: if the minimum RTT is greater than a historical minimum RTT and the maximum BW is less than a historical maximum BW, determining, by the application server, that the network congestion occurs on the link from the application server to the terminal device, wherein the historical minimum RTT is a minimum RTT detected by the application server before the terminal device hands over from the source cell to the target cell, and the historical maximum BW is a maximum BW detected by the application server before the terminal device hands over from the source cell to the target cell. if the minimum RTT is greater than a historical minimum RTT and the maximum BW is less than a historical maximum BW, determining, by the application server, that the network congestion occurs on the link from the application server to the terminal device, wherein the historical minimum RTT is a minimum RTT detected by the application server before the terminal device hands over from the source cell to the target cell, and the historical maximum BW is a maximum BW detected by the application server before the terminal device hands over from the source cell to the target cell. <EOS>