This paper used Nanjing city as the research object for vegetation classification based on IKONOS image.We adopted classification algorithm of decision tree

built knowledge pool on the basis of vegetation spectral information and presented a vegetation classification method based on the spectral information.Then the method was improved by combining textural information and using Homogeneity index.The overall precision of the vegetation classification method based on spectral information was 83.16%

but that of the improved method was upgraded to 91.89%

and kappa coefficient 0.8886.A Quickbird image was used to validate the method

the overall precision was 91.94% and kappa coefficient 0.8783.The result showed the vegetation classification method can classify and discriminate vegetation effectively

and the precision is high.As to vegetation classification with different data source

the method has universality.The vegetation classification method provides theoretical foundation and effective method for extracting vegetation automatically.