Abstract: Correlation analysis was performed to explore the relationships between CODMn, NH4+-N, TP and farm landscape in the Jiulong River watershed. Linear regressions between water quality and farm land percents were also processed in flood season, dry season and average season. The results showed that the total proportion of farm lands located in the slopes less than 15 degrees and greater than 25 degrees were positively correlated with CODMn, NH4+-N and TP concentrations in the water. Contagion index (CONTAG) of farm lands was positively correlated with TP concentrations, and Shannon Diversity Index (SHDI) of farm lands was negatively correlated with TP concentrations. The determinate coefficients were 0.565 and -0.527, respectively. Water eutrophication was susceptible to farm land pollutions in flood season and dry season. The farm lands located in the slopes less than 15 degrees took up 74.3% in the 100m-width riparian buffer. The farm lands located in the riparian buffer and in the deep slopes played a crucial role in water quality management, especially the non-point source pollution control in the Jiulong River watershed.