In order to examine the spatial-temporal differentiation characteristics of the base flow in the Nujiang River Basin, the digital filtering method was used to analyze the base flow in the main stream of the Nujiang River and in the Nantinghe River, which is one of tributaries of the Nujiang River. The results are as follows: (1)The multi-year average base flow index(BFI)was between 0. 71 to 0. 74 for the three hydrological stations over the main stream of the Nujiang River. The multi-year average BFI was around 0. 68 for the two hydrological stations over the Nantinghe River, which was significantly lower than that for the main stream. The volume of base flow and BFI increased from upstream to downstream for both the main stream of the Nujiang River and the Nantinghe River. (2)The variations of the base flow and runoff were basically consistent, and their correlation coefficient exceeded 0. 9. (3)The average intra-annual variations of the base flow and runoff exhibited a single peak pattern, while the average intra-annual BFI had a V-shaped variation for all of the hydrological stations over the main stream of the Nujiang River and the Nantinghe River. However, their variations were not exactly opposite. (4)The BFI values were ranked in the following ascending order: the wet year, the normal year, and the dry year, for the Daojieba Station, which is a typical hydrological station of the main stream of the Nujiang River, and for the Gulaohe Station, which is a typical hydrological station of the Nantinghe River. This is because base flow is more stable than runoff.