Timely and comprehensive monitoring of urban air quality is crucial for managing traffic vehicle emissions and the physical and mental health of residents. This article researches the deployment of traffic vehicle emission monitoring. Mobile pollution source monitoring equipment can accurately track and evaluate exhaust pollutants emitted by motor vehicles on urban road networks, but the equipment is expensive. It is necessary to control costs while meeting the monitoring efficiency requirements. The study introduces turning restrictions to better fit actual traffic conditions and reduce the redundancy of monitoring equipment. The objective is to find monitor locations that can maximize the monitoring of vehicle emissions in the entire traffic network, considering the turning restrictions of the road network.We separate closed and open paths in the road network based on virtual nodes and the maximum flow algorithm to determine the final monitor deployment locations. We introduce coverage to measure the effectiveness of the deployment plan. Finally, by comparing the detection of simulated and real road networks with previous methods, the experimental results show that this method performs well in monitor deployment.