本文首先概述了OFDM 的原理、特征和关键技术，介绍了系统需要的几种同步。然后就同步误差对系统性能的影响进行了简单的分析，表明定时偏差和采样频率偏差将会引入码间干扰，载波频率偏差导致载波间干扰的发生。因此，在OFDM系统接收机中定时的确定、载波频率偏差和采样频率偏差的纠正是信号恢复的关键。之后对OFDM系统同步的几种实现方法进行了介绍，分析了各同步方法的性能。-The paper first outlines the principles of OFDM, features and key technologies, the system needs to introduce several synchronization. Synchronization error and then the impact on system performance for a simple analysis, show that the timing deviation and the sampling frequency deviation will introduce inter-symbol interference, the carrier frequency deviation led to the occurrence of ICI. Therefore, in OFDM system receiver to determine the timing, carrier frequency offset and sampling frequency offset correction signal to restore the key. After the OFDM system to achieve synchronization of several methods of introduction, an analysis of the performance of the synchronization method.