Orthogonal frequency division multiplexing (OFDM) systems are sensitive to time and frequency offset errors. In this paper, a method of joint timing and frequency synchronization for OFDM systems has been proposed based on preamble structure defined in IEEE 802.16 standard. The proposed method in coarse frame detection has good robustness and anti-noise ability. The coarse and fine frequency offset estimations are achieved by choosing different preamble symbol in time domain, which reduces computational complexity. For fine timing synchronization, a method of averaging over two peak values is proposed to improve timing precision, which reduces disadvantages of frequency offset and channel decline. Theoretical analysis and simulation results demonstrate that the proposed joint synchronization method can provide accurate synchronization and appropriate complexity.. thus that method is an optimization method of joint synchronization for IEEE 802.16 OFDM systems.