We developed the Real-time On-road Emission (ROE v1.0) model to obtain the street-scale on-road hot emissions by using real-time big data for traffic provided by the Gaode Map navigation application. The results are close to other emission inventories. Meanwhile, we applied our results to a street-level air quality model for studying the impact of the national holiday traffic volume change on air quality. The model can be further extended to more districts in China or other countries.