This study suggests one hypothesis: The strength between the catchment foreces of urban community parks can be represented to a gravity model. The gravity model is derived from the related of two subjects, witch is related with their distance. A grvity model for the catchments between parks is represented as followed formula: Iij=${alpha}$${ imes}$ $frac{Pi$.$Pj}{${eta}$r}$</TEX>(formula) Here, Iij is a total number of the vistors of park i and j in a year. Pi is population of the catchment area of park i. Pj is population of the catchment area of park j. ${alpha}$and, ${eta}$ are parameters. This formula is testified in the case of Chong-ju community parks.