A method for channel estimation in an Orthogonal Frequency Division Multiplexing (OFDM) system, including: a transmitter determining a distribution density of pilot OFDM symbols according to the maximum Doppler frequency shift supported by the system, and transmitting pilot OFDM symbols and data OFDM symbols based on the distribution density of the pilot OFDM symbols; a receiver estimating frequency-domain channel information of the data OFDM symbols according to the received pilot OFDM symbols. The invention solves the problem of a large performance loss at a high-delay channel and a system with rapidly varying channel. The invention offers a better performance of channel estimation while the channel environment is varying rapidly, enhances the performance of a high-delay channel, makes a data communication system more suitable to a changing environment and makes better performance to the practical channel estimation, so that the data transmission efficiency of the system is increased.