Changchun Jingyuetan Remote Sensing Test Site of Chinese Academy ofSciences is an opening experiment research site of remote sensing.For doing highquality space-borne quantitative remote sensing

we have to do atmospheric correc-tion. For doing this

the understanding of atmospheric optical characteristic over thesite is necessary.In this paper

the spectral extinction and the size distribution ofaerosol are derived and retreived from the data of solar direct spectral radiance ob-servation in 1990（volcanic quiet period）and 1991（volcanic active period）.Owingto these two years related to the different volcanic activities（quiet and active）

the results would provide a foundamental basis of atmospheric correction of remotesensing over that area

also they would be representative of the mid-latitude regionof Northern hemisphere.