A novel two-dimensional channel estimation method based on sliding window is proposed for OFDM-based digital broadcasting system. The method first estimates the channel transfer function at the same subcarrier with an interpolator in time direction, and then processes the received pilots in both multipath spread domain and Doppler spread domain. In this way, it significantly reduces the inter-carrier interference (ICI) due to time-variant shortwave channel and additive white Gaussian noise (AWGN). Moreover, with the sliding window and adjustable sliding step, it can effectively handle the case of different path number as well as different path delays, which demonstrates our method?s robust feature. Simulation demonstrates that the proposed method performs well at typical midwave and short-wave broadcasting channels.