The ground states(S0)of the 2-methyl-4,5-di(α-furyl)oxazole (compound A),2-phenyl-4,5-di(α-furyl)oxazole (compound B),2-α-furyl-4,5-di(α-furyl)oxazole (compound C) and 2-α-furan ethenyl-4,5-di(α-furyl)oxazole (compound D) were optimized with density functional theory (DFT) at B3LYP/6-31+G level,respectively. Single-excitation configuration interaction (CIS) method was used to calculate and optimize the excited states(S1)of the four compounds. The relation among the frontier molecular orbital energy,the absorption spectra,the emission spectra and the structure of the four compounds were discussed. The results show that the theoretically calculated spectrum data well agrees with the experimental value,and especially,the calculated maximum emission spectrum wavelength is more close to the experimental data when the pure density functional theory (DFT-OLYP) method is used. In addition,the frontier molecular orbital energy gap analysis indicates that the larger the conjugation system is the more distinct the red shift of absorption spectrum is.