Both traditional and new spectral characteristic parameters were used to estimate the pigment content of leaves by employing PLS algorithm. Therefore the pigment content of leaves under powdery mildew in processing tomato could be estimated and tested. The result showed that the sensitive bands of original and opposing spectrum were 350～718nm, 719～839nm and 350～718nm, 728～857nm, respectively. Then three groups named PGP, PGT and TTT were composed, including the optimal 9 spectral characteristic parameters from either traditional or new parameters(PSNDa, GNDVI, PSSRa, PSSRb, GM, TPMPa, TPMPb, TPMPc and TPMPd). After estimating the pigment content, the best estimation model was TTT.