An developed mesoscale numerical model of soil-plant-atmosphere continum is used to simulate the characteristics of the planetary boundary layer (PBL) under desert-oasis interaction. Differences are found between them in the PBL depth, wind spiral, profiles of wind, potential temperature and specific humidity, and those in the oasis effect on the air over the desert up- and down- stream are examined, reproducing roughly daytime temperature conversion over oasis and atmospheric humidity conversion over desert next to it. The simulation presents close similarity to observation, leading to further understanding of the PBL structure over a complicated underlying surface.