Orthogonality among subcarriers of OFDM is destroyed by Doppler spread in high mobility environment, causing the decline of system performance. Based on the analyses of ICI principle, a low complexity ICI mitigation method is proposed by equalization in frequency domain. The method is characterized by joint channel estimation of decision feedback and pilot tracking with weighted correction, using estimation result of long training sequence as the initial value. System performance under conditions of different SNR and normalized Doppler shift was tested and compared using new method and conventional methods. Simulations show that the SER performance of our proposed method is satisfactory.