Through site investigation and noise monitoring,the effects of the construction of green belts along the urban trunk roads in Xiamen Island on the attenuation of noise has been studied.The results show that the construction of green belts along the trunk road can be divided into four kinds of types as bellows:type I,single arbor;type II,arbor+shrub;type III,arbor+sub-arbor and type Ⅳ,arbor+sub-arbor+shrub.Their width varied among 4~10 m.The noise-reducing ability (y,dB) of the green belts varied from 0.93 to 12.96 dB with various belt widths (x,m),and can be expressed as following:y=1.2251x+0.2416.Meanwhile the additive attenuation of traffic noise (y,dB) presents a closely linear relationship with the total noise-reducing ability (x,dB) as following:y=0.4535x+0.2698 (R²=0.9242).Meanwhile,the additive attenuation of traffic noise is main affected by the constructions of green belts,which reached 0.93,2.25,4.43 and 6.72 dB,respectively for the above four kinds of construction types.It shows that the width and construction of green belts play the same important role to reduce the traffic noise.