The present invention discloses a channel estimation method and device in an orthogonal frequency division multiplexing system. The method includes steps of: A. grouping physical resource blocks in the bandwidth of the orthogonal frequency division multiplexing system; B. extracting at least one group from groups for channel estimation to acquire a channel coefficient, wherein the number of the extracted groups is less than the total number of groups; C. completing the MIMO demodulation by using the acquired channel coefficient; D. judging whether the channel estimation on the grouping has been completed, if yes, ending, otherwise, returning to step B. The device divides the physical resource blocks (PRB) in the bandwidth of the orthogonal frequency division multiplexing system into several groups and then carries out channel estimation processing on each group of resource blocks successively and individually, so as to achieve memory sharing and save storage amount.