A channel estimation method in a receiver of an OFDM system for receiving carrier signals via a plurality of subcarriers, wherein the channel estimation method comprises the steps of: obtaining an initial channel estimation result of each carrier signal of the subcarriers, and filtering the initial channel estimation results in time domain to obtain a plurality of time filtering results of the carrier signals corresponding to the subcarriers (S 100); dividing the subcarriers into at least one valid section according to at least one null subcarrier comprised in the subcarriers, wherein the subcarriers comprises first subcarriers and second subcarriers, the valid section is corresponded to the first subcarriers for transmitting the carrier signals, while the null subcarrier is corresponded to the second subcarriers and not used for transmitting carrier signals; and characterized by determining according to an index of each of the subcarriers in the valid section whether to select one of N predetermined parameters to be the number of filter taps for the subcarrier corresponding to the index, and filtering the time filtering results in frequency domain according to the filter taps to obtain a channel estimation value of the subcarrier, wherein the index of the subcarrier reflects a distance between the subcarrier and a boundary of the valid section, a smaller predetermined parameter is selected from the N predetermined parameters to be the number of filter taps for the subcarrier when the subcarrier is closer to the boundary of the valid section, and it is determined not to select one of the N predetermined parameters to be the number of filter taps for the subcarrier when the subcarrier is closest to the boundary of the valid section; wherein said N is an integer greater than 1, and the indices of the subcarriers are incremented by 1 in accordance with the sequence of the subcarriers in the valid section. obtaining an initial channel estimation result of each carrier signal of the subcarriers, and filtering the initial channel estimation results in time domain to obtain a plurality of time filtering results of the carrier signals corresponding to the subcarriers (S 100); dividing the subcarriers into at least one valid section according to at least one null subcarrier comprised in the subcarriers, wherein the subcarriers comprises first subcarriers and second subcarriers, the valid section is corresponded to the first subcarriers for transmitting the carrier signals, while the null subcarrier is corresponded to the second subcarriers and not used for transmitting carrier signals; and characterized by determining according to an index of each of the subcarriers in the valid section whether to select one of N predetermined parameters to be the number of filter taps for the subcarrier corresponding to the index, and filtering the time filtering results in frequency domain according to the filter taps to obtain a channel estimation value of the subcarrier, wherein the index of the subcarrier reflects a distance between the subcarrier and a boundary of the valid section, a smaller predetermined parameter is selected from the N predetermined parameters to be the number of filter taps for the subcarrier when the subcarrier is closer to the boundary of the valid section, and it is determined not to select one of the N predetermined parameters to be the number of filter taps for the subcarrier when the subcarrier is closest to the boundary of the valid section; wherein said N is an integer greater than 1, and the indices of the subcarriers are incremented by 1 in accordance with the sequence of the subcarriers in the valid section.