The scanning method of computer worms is an important modeling parameter. Active worms use different methods to scan the network for selecting their victim hosts. Topology-aware active worms scan the network by using the information of the network topology. This property, makes P2P network a suitable place for propagation of this kind of worms. Regarding the instability of network topology, especially in P2P networks, investigating the effect of the join and leave of hosts is completely necessary. In this paper, we study the propagation of topology-aware active worms based on SIR epidemiological model considering the join and leave of hosts. To have a better look at the effect of the join and leave of hosts on the propagation of active worms, the size of epidemic and infectious ratio parameters have been used. The results of this modeling show that the join and leave of hosts have considerable impact on the size of epidemic and the propagation performance of topology-aware active worms.