The dynamic properties of a polaron in DNA stacks are calculated using the time-depended Su-Schrieffer-Heeger model containing the electric field term. The calculation results show that the on-site energy is an important factor influencing the polaron motion. When base pairs with different on-site energy arrange alternatively, the polaron would hop far quickly along this kind of DNA stack. But the polaron would be trapped when the two base pairs with the same on-site energy arrange together. The reason of the above phenomena is revealed according to the calculations. (c) 2006 Elsevier B.V. All rights reserved.