A theoretical study on three 2-styrylbenzothiazole compounds with better activity of killing moulds by semi-empirical method is given in this paper. Their geometric configurations have been optimized by semi-empirical method RHF/AM1. The results of optimization show that most of the atoms are in the same plane. Their smallest vibrational frequencies are 13.50

9.66

7.53 cm

-1

and there is no imaginary frequency in vibrational analysis. Energy differences between HOMO and LUMO are 7.838

7.706 and 7.288 eV. Δ

E

is so small that the electrons can be easily excited. Their fluorescence spectra have also been calculated by RHF/CIS. The values are essentially consistent with experimental values. All the spectra data are calculated by ideal gas models

but the experimental values are determined in solutions. So it is permitted that there are some differences between them.