With Huckel tight-binding method, we have calculated the electronic structures for banana-shaped liquid crystal 1,3-phenylene bis [4-(4'-nonyloxy) phenyliminomethyl] benzoate, and the effects of the central core, the linkages (-COO- and -CH=N-) and the alkyl tails in the two-branched legs of the banana-shaped liquid crystal on the electronic structures have been discussed. Our results indicate that the energy differences between the lowest unoccupied molecular orbit and the highest occupied molecular orbit are predominantly affected by the central core and the linkages but not too much by the alkyl tails in the two branched legs of the banana-shaped liquid crystal.