Abstract: Aim To improve the real time performance of data transmission in a DIS based on TCP/IP Methods Characteristics of communication in DIS are analyzed Some improvements are made to the standard TCP/IP protocol according to the requirements of DIS communication service thus the QTCP is proposed Results QTCP,an improved protocol of standard TCP protocol,reduces some overhead of TCP unnecessary to DIS The protocol efficiency is enhanced and the real time performance of data transmission improved Conclusion Real time performance of data transmission in DIS is improved by making some necessary changes to standard TCP/IP