This paper studied four types of green space in urban on the reduction of heat island effect. The authors selected four typical types of green space and their adjacent bare plot in changsha city to carry out field observations of temperature, humidity and obtained data. By statistical analysis, the results showed that: different types of green space had different effects to reduce the urban heat island; cooling effect and humidifying effect were showed that: the arbor forests’ was higher than arbor-shrubberys’ than thicket’s than grasslands’. Temperature changing index of arbor forest, arbor-shrubbery, thicket, and grassland were 7.32, 6.59, 5.33 and 4.10. Humidity changing index were 16.87, 13.23, 9.42, 7.61 in order. The conclusion showed that: different types of green space, because their internal structure and the vertical structure were different, it was different to reduce the urban heat island intensity, the capability reducing heat island effect on four types of green space in changsha was the arbor forests>arbor-shrubbery>thicket>grassland; Changsha should increase construction area of the arbor forests and arbor-shrubbery, to reduce construction area of thicket and grassland for reduction of the urban heat island effect in building green space.