In this paper, the author quantified the city traffic environment carrying capacity on the basis of the relationships among traffic environment carrying capacity、the bearing capacity of the urban traffic and urban environmental capacity. And based on the actual vehicle maintain models of Jinan city, the author adjusted the formula of motor vehicle exhaust emission source ,then fixed the OPSM street valley diffusion model of China's big cities in combination with the practical situation of Jinan, and established a new TECC calculation formula based on the traffic environmental bearing capacity of single factor contaminant, finally calculated Jinan's threshold and predicted years of threshold, which would provide reference for the government and related departments to formulate the traffic development and management measures, and also would offer a thought for the research of urban motor vehicle development scale.