Abstract: In this paper, we reported a modified Huckel molecular orbital (MHMO) method, which is driected to the calculations for linear alternant polyenes.MHMOcalculations for linear alternant polyenes with n_c =4-50 were carried out by DJS-21 electronic digital computer. we have obtained pi-electron energies, MHMOcoefficients, et al.. Comparison of predicted and observed longest-wave length absorptions (or wave numbers) for linear alternant polyenes shows fair agreement with experiment. These predicted results are close to that which is calculated by the SCF MO. It is a most distinct improvement compared with HMO.