The Luan River Basin is an essentially ecological barrier and water conservation area in the Beijing-Tianjin-Hebei region. Notwithstanding, there are still problems concerning soil erosion and substandard river water quality in the basin. On the basis of the measured data, the parameters of the InVEST model were calibrated to quantitatively evaluate the soil conservation and water purification services and their temporal and spatial variation characteristics in each ecological region of the Luan River Basin in 2005, 2010 and 2015, respectively. Correlation analysis and Moran' I index were employed to examine the mechanism of action and relationship of trade-offs and synergies between the two services. Meanwhile, we discussed how the two services would be affected by changes in land use and climate. The results demonstrated that the annually average soil conservation intensity of the Luanhe River Basin in 2005, 2010 and 2015 was 136.45 t/hm², displaying the characteristics of first strengthening and then decreasing slightly. Notably, the spatial distribution pattern showed an increase from northwest to southeast. The averagely annual output of total nitrogen (TN) and total phosphorus (TP) in the basin was 1526.73 t and 82.89 t, respectively. The lower and middle portions of the basin produced the majority of the output, which grew yearly. Additionally, the overall water purification capacity of the basin was weakened. There was a significant connection between the concentration of TN and TP in the water body in the basin and the amount of sediment that entered the river. The relationship between soil conservation and water purification services has changed from synergy to trade-off as a whole. The spatial difference lies in the fact that woodland and grassland concentrated areas are overwhelmingly based on synergy, whereas the agricultural and pastoral belt areas are predominately based on trade-off relationships.