[Objective] We studied the dust retention capacity and air purification abilities of different forests (mixed broad-leaved forest, mixed coniferous and broad-leaved forest, mixed cypress forest, mixed coniferous forest and deciduous pine forest) in Chongqing City, which provides scientific basis for the protection and early warning about destruction of forest ecosystems in Chongqing City.[Methods] Spatial and temporal monitoring were carried out on the main forest types, which indicated that the forests providing negative oxygen ions, dust retention, and absorption and transformation of air pollutants in Chongqing City.[Results] The dust retention capacity of these forests was significantly (p<0.05) more than non-forested areas, and the average dust catching quantity was in order of mixed broad-leaved forest > mixed coniferous and broad-leaved forest > mixed cypress forest > mixed coniferous forest > deciduous pine forest. The foliar dust retention of particles in most was total suspended particulate (TSP), while PM₁₀ and PM_2.5 had a certain amount of adsorption. The dust relative content of PM_2.5, PM₁₀ and TSP in mixed broad-leaved forest was the greatest. The dust particle size adsorbed by different green plants ranged from 2.5 to 100 μm, most concentrated under 100 μm (more than 99%). The number of negative oxygen ions and positive oxygen ions produced was highest in the mixed broad-leaved forest > deciduous pine forest > mixed coniferous and broad-leaved forest > mixed coniferous forest > mixed cypress forest, and the value of dust retention, SO₂, HF and NO_x absorption was the greatest in the mixed broad-leaved forest > deciduous pine forest > mixed coniferous and broad-leaved forest > mixed coniferous forest > mixed cypress forest.[Conclusion] The dust pollution in the mixed broad-leaved forest in Chongqing City is serious, but at the same time,the mixed broad-leaved forest had a strong air purification capacity.