Abstract: To analyze the carrier estimation performance, wide-spectrum auto-relation algorithm and wide-spectrum L&R algorithm, which can realize wide frequency offset range estimation based FFT algorithm, are discussed in this paper. Based on the discussion, combining the pilot of TDMA signal with vivid frequency distinguishability of CZT(chirp ztransform) algorithm, an improved algorithm which fits for carrier synchronization of low signaltonoise ratio(SNR) signal with large carrier offset range is designed. The dataaided(DA) carrier synchronization using the pilot of TDMA signal can efficiently shorten the carrier offset range of low SNR signal, then using the CZT algorithm to reduce the frequency offset range further, the accurate carrier frequency offset will be gotten by non-data-aided(NDA) auto-relation algorithm finally. The complexity of the improved algorithm is a little higher than wide-spectrum auto-relation algorithm, but much lower than wide-spectrum L&R algorithm. Comparing with other algorithms, simulation results show that the improved algorithm has a good and steady performance under low SNR(3-6dB).