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.