The spatial scale effect in airborne hyperspectral CASI data information extraction was studied from spectral, spatial and frequency aspects. The collection means by variable flight altitude were discussed firstly. And three kinds of methods to extract five typical objects were researched and their extraction accuracy were evaluated quantitatively in the end. Overall accuracy, the optimal information extraction method of the five typical objects and their extraction scale, the pertinences of the three kinds of extraction methods were concluded. Results are not only provide a guidance for CASI data collection, but also have an important significance for subtle, quantification and thematic extraction of an object from hyperspectral remote sensing.