By the development of network applications, network security issues are getting more and more important. This paper proposes a multiple-pattern matching algorithm for the network intrusion detection systems based on the GPU (Graphics Processing Units). The highly parallelism of the GPU computation power is used to inspect the packet content in parallel. The performance of the proposed approach is analyzed through evaluations such as using various texture formats and different implementations. Experimental results indicate that the performance of the proposed approach is twice of that of the modified Wu-Manber algorithm used in Snort. The proposed approach makes a commodity and cheap GPU card as a high performance pattern matching co-processor.