Abstract: The traditional TCP congestion avoidance mechanism has strong bias against links with higher round-trip delays. As the competing TCP connection increase, the fairness and utilization of the sharing link degrades dramatically. The CR, IBK, CANIT examined firstly, and then a new fairness algorithm “K and additive increase ratio” (KIR) is proposed to correct the bias against these long connections. The new algorithm in which a new arithmetic formula “K” is used for the first time smoothly modifies the long and short round-trip delay link congestion avoidance algorithm. A series simulation is chosen and the different algorithm characteristic is analyzed. With these modifications, the simulation result show that the algorithm not only can improve TCP fairness, but can obtain good throughput performance as well. Finally, the effectiveness of KIR is proved by the simulation combined with NewReno, Sack and Tcpw under the GEO satellite environment.