First, precipitation is infiltrated into subsurface or is discharged through surface. Infiltration water is discharged into groundwater or is evaporated. This is called precipitation partitioning. This phenomenon can be quantified by the Horton index. This study analyzed effect of climate and watershed characteristics on precipitation partitioning using the Horton index. In the Nakdong river basin, the Horton index is primarily affected by precipitation of climate factors. Considering precipitation and landscape characteristics of watershed, predictability of the Horton index is improved. Especially, average slope of watershed is significant indicator among landscape characteristics.Key words