Remote sensing evapotranspiration (ET) data was employed to investigate its ability of compensating for hydrological data in the study area, and its impact on the simulation performance of ET and runoff in the SWAT model. Xixian Basin in the upstream of Huaihe River was chosen as the study area. The data of monitored runoff and remote sensing ET (MOD16A2) were used in establishing three scenarios of parameter calibration, namely, S1-only use the monitored runoff data to calibrate parameters, S2-only use the remote sensing ET data to calibrate parameters, S3-use both data to calibrate parameters simultaneously. Then the simulation performance of each scenario was analyzed accordingly. The results indicated that compared with S1, the runoff simulation accuracy (NS coefficient) decreased both for S2 and S3, but with a significant improvement seen in S3. As for the ET simulation on the subbasin scale, the NS coefficient showed an increasing tendency from S1 to S3. Upon application of both data, the number of subbasins with increased NS coefficient in S3 accounted for 46% of the total subbasins compared to S2. This paper employed remote sensing ET data in a step-wise way to explore its application to the SWAT modeling and the impact on parameter calibration, and then analyzed the changes it brought into runoff and ET simulation performances. This method can be applied to other hydrological models, and provide valuable information for water resources management and utilization.