Abstract: Low temperature plasma technologies have been widely used in many high_tech fields today. The fields applying plasma are still enlarged quickly.The higher demands have been arised for the plasma high density and the large area planar uniformed plasma was required as one of the most urgent demands now.The principles of surface microwave forming were introduced. Radial,azimuthal and axial distribution of the electron density and temperature of Ar plasma in the plasma source excited by surface_microwave were measured with Langmuir probe.The relationship that the uniform degree of the electron density and the temperature distribution along radius and azimuth changes with the microwave power,the gas pressure and the antenna shape was found that the power and the antenna shape is not important for the azimuthal and radial uniform degree,respectively.So a conclusion reached that large area planar high density plasma could be produced by improving the antenna shape,enhancing the microwave power and choosing the proper pressure.