The invention discloses a method for realizing synchronization of a carrier and a sampling clock. The method comprises the steps of: determining a carrier frequency deviation and a sampling clock frequency deviation according to the received downlink signal; carrying out carrier frequency compensation according to uplink to-be-sent data; and carrying out sampling clock frequency compensation according to the uplink to-be-sent data. The invention also provides a user site device, which comprises a carrier frequency deviation measuring unit, a frequency deviation compensating unit, a sampling clock frequency deviation measuring unit and a clock sampling frequency compensating unit. According to the invention, the problem of synchronization of medium-short distance messaging systems based on control is solved, especially, the problem of synchronization when uplink multiple users are accessed in parallel is solved. The synchronization of the time and the frequency is mainly completed by an STA according to a downlink synchronization precursor, the deviation of the frequency and the sampling clock frequency is preprocessed, the synchronization problem is simplified to the signal-user synchronization problem, so that multiple access interference is eliminated without a complicated algorithm when a receiving end separates data of multiple users.