The present invention relates to technique for frame synchronization in a distributed MIMO-OFDM system, and the method thereof comprises: generating step: generating preambles for synchronization at respective transmitting antennas using PN sequences with different lengths which have one-to-one correspondence to the respective transmitting antennas by a transmitter; locating step: performing calculation using correlation calculators with width of window corresponding to the lengths of the PN sequences to locate head of frame by a receiver. The present invention proposes a solution for frame synchronization using sequences with non-equal periods in a distributed MIMO-OFDM system, and head of the frames transmitting from respective transmitting antennas can be accurately found using correlation calculation at a receiver by means of the technique. Since the PN sequences with different lengths are used at respective transmitting antennas to form corresponding preambles, when a correlation calculator corresponding to a certain transmitting antenna is used, all data or preambles at other antennas can not produce interference, i.e. delay between distributed transmitting antennas can not has an effect on detection of head of frame at a certain transmitting antenna.