Along with the increasing demands on traffics, urban traffic is becoming more serious. Whether we can relieve the urban traffic pressure by opening the roads of the closed residential districts deserves our research. In this paper, a network model of linear programming based on the shortest path of traffic diversion is built. Three evaluation indexes are put forward including the factor of traffic improvement, the average degree of traffic saturation, and the standard deviation of traffic saturation, to evaluate and contrast the traffic flow and the degree of road usage and reflect the specific influence of opening the roads of closed residential district on urban traffics. In this paper, two types of data of traffic network and traffic flow are emulated and solved through model. The results show that although the density of road network increases, which may reduce the total traffic burden, the opening of all residential districts cannot relieve the urban traffic pressure. The size, location, external and internal road conditions of residential districts and many other factors can affect the traffic state of road network. So, this issue cannot be generalized. It is necessary to evaluate the specific conditions of the residential districts and the roads around before determining whether the roads of the district can be opened or not.