Based on the Meijninger(2002) model and the continuous flux measurement over a 31-year aged mixed plantation in the hilly zone of the North China from May to September in 2009，the source area and footprint of the plantation flux for large aperture scintillometer(LAS) method were calculated in the main growing season . The results showed that:①The range of source area under NW that is the smallest in stable stratification conditions is 11.8% bigger then the source area under SW that is the biggest in unstable stratification conditions. ②The range of source area is 1.1483 km2 at 8:00 when stratification conditions become unstable exactly; The range of source area source area is 0.4518 km2 at 11:00 as is the smallest in ae day. The range of source area becomes 0.7137 km2 from 0.4779 km2, when stratification conditions become stable from unstable. The changing trend of source area is consistent with radiation and temperature.③The range of source area is 1.834 km2,1.680 km2,2.043 km2,1.671km2,1.380 km2, in May, June, July, August, September respectirely.