OFDM system performance is more sensitive to frequency offset and timing error than single-carrier systems. In this paper, the integer frequency offset is estimated based on the special pilot symbols; the timing error estimation value is obtained by the correlation characteristic of the pseudo noise sequence (PN-sequence); then the fractional frequency offset can be estimated grounded on the correlation of pilots. In order to improve the accuracy of the estimator, oversampling technology is adopted. The simulation shows that the good performance is gained, the results approach the Modified Cramer - Rao lower Bound (MCRLB).