An　extension　linear　spectral　model　based　on　total　least　square　algorithm　is　proposed,　and　iteratively　abstract　the　better　endmembers　and　physically　based　constrained　algorithm　with　this　model　are　presented.　The　results　show　that　the　proposed　model　provides　better　accuracy　than　traditional　least　square　method,　the　total　estimating　precision　improves　by　10%-20%.