This paper provides a complete packet-level topology aware worm simulation model based on worm targets discovery, worm code transmission and worm activation, and designs a directed Small World topology generation algorithm. Then, through selective abstraction, this paper implements a complement packet-level topology aware worm simulation system. Finally, with simulation experiments, the paper analyzes the impacts of topology structure and worm activation on worm propagation. The results of simulation experiments show that this simulation system can provide great support for topology aware worm research.