Abstract: In order to estimate timing-frequency synchronization parameters quickly in the process of downlink synchronization for time division long term evolution (TD-LTE) system, a low complexity joint estimation of timing-frequency synchronization based on the time-domain symmetry character of primary synchronization signal is presented. The principle and performance are detailed analyzed in theory. Simulation results demonstrate that, compared with existing algorithm, the proposed algorithm can ensure the precision and reduces the computational complexity greatly, and satisfy the requirement of real-time.