Abstract: Taking four green belts with different internal constitutions and  five green belts with different canopy densities along the west fourth ring road of Beijing as test objects, and by using small-scale quantitative measurement method, this paper studied the relationships between different structure urban green belts (width 42 m) and temperature-humidity effect in Beijing. Comparing with the control, lawn had no obvious effect on the decrease of air temperature and the increase of relative humidity, while shrub-herbage, tree-shrub-herbage, and tree-herbage had significant effect. When the canopy density was 10%-31%, green belts had definite effect on the decrease of air temperature and the increase of relative humidity; when the canopy density reached 44%, the effect became significant; and when the canopy density exceeded 67%, the effect was significant and stable.

Key words: green belt, internal constitution, canopy density, temperature-humidity effect, heat island effect