Thank you guy, I knew the site of nds list, it's cool, but it's not my need...
I am coding for a batch tool for my nds collection, one of the functions is extract icon from the rom
And it seems that the file extract with "ndstool -x xxx.nds -b xxx.bmp" just like "ndstool -x xxx.nds -t banner.bin", it's not the icon file, it's a bug ?