Abstract: Ad hoc network is not deployed on a large scale, and researches in this area are mostly simulation based on mobility models. The research on node space probabilistic distribution of mobility model plays a very important role in studying many relevant characteristics of ad hoc network. However, there are many drawbacks on existing mobile models, e.g. unrealistic movement scenarios, non-uniform distribution, low connectivity, etc. On the basis of analysis of these models, a novel mobile model based on circle movement is proposed and the space probability distribution of this mobile model is deeply investigated. By the analyses of the probability and average length of the events that contribute to the node space distribution, the exact equation of the node asymptotically stationary distribution for movement is derived on a 2D region. Its advantages such as uniform distribution are validated through simulations by various settings of the mobility parameters. Simulation results show that this new model avoids the above drawbacks. Given a deep understanding of the behavior of this new model, the research results are of practical value and provide exact theoretical model for simulation and evaluation of ad hoc network performance.