In order to explore the spatial and temporal distribution characteristics of phytoplankton functional groups in Sanbanxi Reservoir of Guizhou Province, phytoplankton samples collected in different depths in the dry season (November 2012), level period (April 2013) and wet season (July 2013) were characterized. Results suggested that there were 21 functional groups of phytoplankton. The dominant functional groups had obvious distribution patterns: P+Xl+D+J in the dry season, P+B+C+G in the level period and M+H1+S1+J in the wet season. The dominant functional groups changed at about 10 m depth during the level period and wet season, and changed at 70 m depth during the dry season. This was caused by the different characteristics of the water thermal stratification and nutrient distribution in different seasons. The spatial and temporal distribution patterns of phytoplankton functional groups were affected by climate change. The variation of water temperature, pH and N/P were the main factors leading to the change of phytoplankton functional groups. The strategy of phytoplankton growth followed the law: CR/C/S in the dry seasonR/CR/CS in the level periodS/CS/CR/R in the wet season. The composition of phytoplankton functional groups showed that Sanbanxi Reservoir was in the eutrophication state.