Rapid soil water infiltration in green space plays an important role in the alleviation of flood hazard in urban areas, so its accurate measurement is very critical for the assessment of flood storage capacity in cities. However, the soil infiltration rate of green space in different functional zones varied greatly due to the high spatial heterogeneity in urban soil. In this paper, soil infiltration rate was measured using a double ring infiltrometer and its influencing factors were analyzed in Haizhu National Wetland Park, Guangzhou city. The results indicated that:(1) soil water infiltration capacity in green space of the Haizhu National Wetland Park could be classified as the middle to relatively high level. However, the soil physical clay content and bulk density in our study area were relatively higher, while soil non-capillary porosity was relatively lower in green space soil compared with the natural soil, which could be attributed to its soil source mainly transported from other places, such as pond sludge. Moreover, heavy soil compactions from both mechanical and human activities, as well as mixture of anthropogenic intrusions due to the mismanagement of urban solid waste, which all contributed to the inhibition of soil water infiltration in urban green space. (2) Plantation of shrubs and grasses could greatly improve the soil water infiltration capacity in surface soil of urban green space compared with the plantation of trees and grasses, which was due to the relatively shallow root distribution of shrubs in soils. In addition, more difficulty in cleaning the leaf and branch litter, and higher decomposition rate with finer roots were more commonly observed in urban green space with shrubs and grasses, which both contributed to the rapid feedback of litter from leaves, branches and roots, facilitated the increase of the surface soil organic content, and further enhanced the soil water infiltration capacity in urban green space. (3) With higher R² and lower RMSE, the variation of cumulative infiltration of soil water into the urban green space could be better simulated through the Kostiakov model. The establishment and management of urban green space should focus more on the combined plantation of trees, shrubs and grasses, especially the increase of shrub plantations, while reduce the use of soil from other places, particularly the soil with high physical clay content, and weaken the soil compaction by building the specified passage and recreation area, which will balance the functions between leisure and flood storage in urban green space, and facilitate the development of sponge city in Guangzhou.