Making use of the data of June,July and August 2001 and the mesoscale model-MM5V3.5,the capability experiments of summer climate simulation aiming at the eologically vulnerable areas in the west of Liaoning are performed in this paper,and this changes of summer mean tempreture due to the degeneration and resuming of vegetation are simulated.Results show that after the degeneration of vegetation in some areas in the west of Liaoning,the summer average temperature obviously increases while the summer average temperature drops due to the local resuming of vegetation.In the areas around the vegetation change regions,the summer average temperature also alters to some degree.At the same time,the vegetation change affects the temperature and pressure fields aloft.