Road traffic is a major source of in urban areas with far-reaching and wide-range effect to human. It produces disturbance and inversely impacts more than other forms of noise. Urban traffic noise impact assessment has thus become an active environmental acoustics domain. This paper firstly measures the traffic noise in the truck lines in Nanchang city and estimates it. Then this paper finds out the cause of the traffic noise in Nanchang city. Thirdly this paper gives some suggestions on the noise pollution.