Under the background of promoting the block system, the paper mainly focuses on the impact on the surrounding road capacity caused by the openness of the communities. Firstly, the basic capacity model of the road is established by using Newton’s second law. Then, based on the openness of the district, we analyze the probabilities of the drivers choosing the intersection and exit of the district and the delay rate of the crossing. So we establish the modified road capacity model. Finally, according to the actual situation, the road structure in the surrounding areas and intersection type is divided, and the influence coefficient of the road is introduced, which are used to establish the vehicle traffic mathematical model to quantitatively analyze whether the district opening can promote the road capacity, thus providing a certain theoretical basis for the open policy.