This research intends to investigate the watershed morphometry factors that affect the watershed base flow. The methodology consists of data screening on rainfall-flood hydrograph (single peak), separating the direct run-off and base flow, identification the characteristic of watershed physical parameter, and finding the relation between the watershed physical parameter and base flow. The result shows that watershed area (A), watershed circumference (P), main river length (Ld), total river length (Ltot), and topography factor (T) are influencing the watershed base flow