Abstract. The previous TCP protocol cannot predict congestion. Only when the sender receives more than three acknowledgements or the retransmission timer is out can it realize that congestion has occurred. We train the linear neural network by using round-trip time and current TCP throughput as its inputs. As a result, we get the decision boundary, which could predict whether the current network is in congestion or not. Simulation results show that, when applied to TCP congestion control, it can effectively predict the occurrence of congestion, so congestion window could make adjustments as soon as possible to reduce the probability of congestion collapse.