The invention discloses a new synchronous combination method of an OFDM system, relating to communication technical field and aimed at realizing synchronization of an OFDM system. The method includes the following processes: OFDM signals r(n) are received; symbol synchronization and fractional frequency offset(FFO) estimation and compensation are realized through existing ML synchronization algorithm in time domain; fast Fourier transform is carried out to the signals so as to realize transformation from time domain to frequency domain; based on the transformation, integer frequency offset(IFO) estimation is carried out according to the offset position of a virtual carrier; integer frequency offset compensation is done in frequency domain; a Flag marker bit is estimated; if Flag is equal to 0, IFO estimation and compensation in frequency domain will be carried out repeatedly; if Flag is equal to 1, combined estimation and compensation in time domain and frequency domain synchronously to the OFDM system are carried out and precise sync signal Xk` is outputted. The new synchronous combination method is applicable to digital video broadcasting (DVB) systems, digital audio broadcasting (DAB) systems as well as wireless communication systems, such as 802.11a, and 802.16.