A method and system for achieving frequency domain scheduling in a time division duplex system is disclosed, the method comprising: a first device transmits a non pre-coded reference symbol to a second device; from the reference symbol, the second device obtains a channel impulse response matrix experienced by the reference symbol transmitted from the first device, and according to the channel impulse response matrix, obtains linear spatial domain pre-coding matrix of candidate physical resource blocks used in transmitting data to the first device; from the channel impulse response matrix and the linear spatial domain pre-coding matrix, the second device obtains the channel quality indication of the candidate physical resource blocks; and performs the frequency domain scheduling according to the channel quality indication. The use of the method not only solves the problem in the prior art that the frequency domain scheduling is unable to be performed when a channel sounding method is employed, but also the contradiction in the use of the frequency domain scheduling and the linear spatial domain pre-coding. A communication system is also disclosed.