A method of adjusting quality of service (QoS) with respect to changes in a transmission environment of a mobile terminal receiving data based on a stream control transmission protocol (SCTP) session. When the transmission environment of the mobile terminal receiving data based on the SCTP session changes, the mobile terminal transmits link information indicating a new transmission environment to a destination node, and the destination node adjusts the quality of data or the size of a transmission window based on the link information. Thus, without adding separate network devices, the QoS of the data being transmitted can be adjusted with respect to the changed transmission environment, only by adding functions with software to the transmission terminal and the reception terminal. Also, since the destination node manually adjusts the transmission window according to the link information, packet loss can be minimized compared to the conventional congestion control method.