Abstract: In this paper a fast classification algorithm which uses table-look-up method is proposed. Both theoretical and experimental results have shown that (1) in two dimensional case it can reduce the computer time to the same order needed for the data I/O; (2) in the case of more than two dimensions it can save more than half of computer time. The classification accuracy is not affected by the use of table-look-up method. The algorithm is most suitable for computers without floating-point processor while there are many remote-sensed data to be processed.