In this paper some new hypotheses corresponding to cleft mechanisms and peak-heightcquation of mass spectra for conjugated organic compounds are proposed on the basis of theprevious work. The energies of the π-electrons of the molecular ions and various fragments, andthe super-delocalizability among the nuclei of the molecular ion have been calculated by usingmodified HMO method and group theory. The mass spectra of five aromatic conjugated poly-enic aldehydes, benzaldehyde, cinnamaldehyde, 5-phenyl-2 : 4 :-pen-tadienal, 7-phenyl-2:4:6-heptatrienal and 11-phenyl-2:4:6:8:10-undeca pentaenal are quantitatively explained. Thevalues of theoretically calculated peak-height are better conformed with the experimental result.and the correlative coefficients in the main peak-height equation cleft are all above 0.96.This fact reveals that a new way for the quantitative calculation on mass spectroscopy isprovided. In this paper some new hypotheses corresponding to cleft mechanisms and peak-height cquation of mass spectra for conjugated organic compounds are proposed on the basis of the previous work. The energies of the π-electrons of the molecular ions and various fragments, and the super-delocalizability among the nuclei of the molecular ion have been calculated by using modified HMO method and group theory. The mass spectra of five conjugated conjugated poly-enic aldehydes, benzaldehyde, cinnamaldehyde, 5-phenyl- 2: 4: 6-heptatrienal and 11-phenyl-2: 4: 6: 8: 10-undeca pentaenal are quantitatively explained. Thevalues ​​of theoretically calculated peak-height are better conformed with the experimental result. And the correlative coefficients in the main peak-height equation cleft are all above 0.96. This fact reveals that a new way for the quantitative calculation on mass spectroscopy isprovided.