The effect of the acrylonitrile content on the structure and dynamic behavior of nitrile rubber was systematically studied during glass transition process by employing all atom molecular dynamics simulation. For the static property, the polymer density and energy were calculated. The polymer density, non-bond energy and torsional energy are found to play an important role during glass transition process. For the dynamic property, the translational mobility, bond reorientation mobility and dynamic heterogeneity on chain backbone were analyzed. The mobility on chain backbone declines with improving acrylonitrile content. Meanwhile, the glass transition temperature (Tg) obtained from the non-bond energy and torsional energy method is larger than that from the polymer density method. Furthermore, the Tg obtained from the dynamic heterogeneity method is largest compared to that from the bond reorientation mobility or atom translational mobility method. Especially, according to the mean-square fluctuations of the backbone atoms, the immobile atoms were distinguished. Then, the percolation probability of the immobile domain was analyzed by characterizing the size of the largest immobile domain and number of the immobile domains. By observing the snapshots of the mean-square fluctuations of atoms, the percolation transition of the immobile domains was clearly observed, which can help to understand the glass transition process for different acrylonitrile contents.