[Objective] The watershed division in complex topography area was conducted in order to provide basic data for regional ecological watershed construction and planning.[Methods] Hubei Province was selected as a case study area

where covers mountainous

hill land

plain

many rivers and lakes. Firstly

small watersheds were extracted automatically by using the ArcGIS base on DEM data. Then

small watersheds in the mountains were merged and revised manually with the assistance of gullies

remote sensing images and residential data. For plains

the conventional gullies were replaced by the high-precision river systems. At last

we analyzed the suitable threshold value

frequency

precision and river network density.[Results] There were 5 806 small watersheds in Hubei Province. The watersheds with areas changed from 30 to 50 km2 account for 60% of the total number. Watersheds with area small than 20 km2 had low-precision and dense in plain. In general

the classification accuracy of small watershed in mountainous area was higher than that in plain area

while the average river network density shows the opposite.[Conclusion] The results show the human-machine interaction correction could be used for the small watershed's division in order to get a better result. The accuracy of automatic division of small watersheds in plain area is lower than that in mountainous area

which needs to be corrected manually with high precision water systems.