The computation complexity of Lapped Biorthogonal Transform (LBT) is high and the precision of its integer algorithm is lower.To overcome these shortcuts,a fixed point algorithm of LBT is proposed.Based on the approximation of numbers in Q format,fixed point is used to approximate the value of trigonometric function of the rotation matrix in the algorithm.And the parallel computing of the algorithm in TMS320C6000 DSP is studied by using assignment partition,complex instruction,software pipeline and optimization method to improve the processing speed.The algorithm has been used in prototype data compression equipment of a spy satellite.Image coding experiments show that coding performance of the algorithm is very competitive with CDF9/7 wavelet and the complexity of the algorithm is far low.