Intrusion detection system(IDS) is becoming a critical component of network security. However,the performance of many proposed intelligent intrusion detection models is still not competent to be applied to real network security. This paper aims to explore a novel and effective approach to significantly improve the performance of IDS. An intrusion detection model with twin support vector machines(TWSVMs) is proposed.In this model, an efficient algorithm is also proposed to determine the parameter of TWSVMs. The performance of the proposed intrusion detection model is evaluated with KDD’99 dataset and is compared with those of some recent intrusion detection models. The results demonstrate that the proposed intrusion detection model achieves remarkable improvement in intrusion detection rate and more balanced performance on each type of attacks.Moreover, TWSVMs consume much less training time than standard support vector machines(SVMs). However, the performance of many proposed intelligent intrusion detection models is still not competent to be applied to real network security. This paper aims to explore a novel and effective approach to significantly improve the performance of IDS. An intrusion detection model with twin support vector machines (TWSVMs) is proposed.In this model, an efficient algorithm is also proposed to determine the parameter of TWSVMs. The performance of the proposed intrusion detection model is evaluated with KDD ’99 dataset and is compared with those of some recent intrusion detection models. The results demonstrate that the proposed intrusion detection model achievious remarkable improvement in intrusion detection rate and more balanced performance on each type of attacks.Moreover, TWSVMs consume much less training time than standard support vector machines (SVMs).