With the development of IPv6, it is taken as a natural cover to defend against Internet worm due to its huge address space. We demonstrate that an intelligent worm can compromise the IPv6 network according to using adaptive means. Based on the analysis of the scanning strategies in IPv6 network and correlative typical propagation technologies, a general worm model named Next Generation Internet worm model (NGIWM) is established for analyzing the propagation of IPv6 worm which is made up of three layers. The three layers have the function to accelerate the spread of NGIWM, and make NGIWM has the capability to form large scale of prevalence. The result indicates the rationality of scanning strategies and the effectiveness of the propagation compared to IPv4 network worm. The simulation shows that the implementation of NGIWM has the potential to become a major threat to IPv6 network. The performance of the worm depends heavily on domain name generator algorithm and scanning strategies in local network. We also analyze the effect of experiment parameters on the model in the simulation part. In the future, detailed implementation of the proposed model and more defense mechanisms are to be studied.