▎ 摘　　要

The electronic structures and the imaginary part of dielectric function ,epsilon2(omega), of two kinds of microtubules with different axis orientations axe calculated. The comparison of the epsilon2(omega) curves of two considered kinds of tubules shows that, the behaviors of their epsilon2(omega) curves corresponding to the transitions between pi bands near the Fermi energy are very different. Our calculation also indicates that, the difference of optical properties is quite independent of the band-structures E(nK), but is related with the quantum momentum matrix.