To overcome the problems of ISVM and TSVM in intrusion detection,this paper improves PTSVM for network intrusion data features and designs a method with area marked tendency.It makes the training of PTSVM more quickly and accurately,leading a split plane more close to the optimum.Experiments show that intrusion detection based on improved PTSVM has an obvious advantage in training and testing speed,and it greatly improves the detection rate of attack samples.