Estimating ecosystem evapotranspiration (ET) using model simulation is of great significance to study regionally spatiotemporal variation of water resources and to evaluate effects of climate change on water management. Based on MODIS-ET model, ecosystem ET in Panzhihua-Xichang (Pan-xi) tobacco planting area was simulated by using remote sensing data and meteorological data from January to October in 2016. The model was parameterized and validated by field flux observation data. Results showed that the ET values calculated by MODIS-ET model with defaulted parameters were about 12.8% lower than observation values. The efficiency coefficient was 0.767, and the average error in early growth period (DOY 105 ~ 161) was the highest. After parameterization on the basis of field observation data, the dynamic curve of ET was consistent with measured dynamic curve. The slope of linear regression was 0.997, and the efficiency coefficient was 0.808. These results proved that MODIS-ET model has efficient applicability after parameterization in the study area. The study could provide an applicable ET dataset to support study on water and heat balance in Pan-xi tobacco planting area.