Using a non-rigid bipolaron model modified with the correction of the pseudogap effect, we have studied the temperature (T) dependence of the Hall coefficient (RH) in the normal state of several typical high-Tc superconductors (e.g. YBa2Cu3O7-δ). The results are in agreement with experiments. It is suggested that the positive maximum in the RH-T diagram corresponds to a point near the bottom of the pseudogap. We have also found that for these high-Tc superconductors, W-T can be scaled into a single universal function form, where W is the bandwidth of the non-rigid bipolaron system.