Abstract-Time-and -frequency sychronization is critical point in OFDM based system such as DVB-T/H system. sychronizer has a function to estimate and compensate for the carrier frequency and time offset of the received signal. false in time and frequency estimation will cause inter carrier interference (ICI) and inter symbol interference (ISI). this paper proposes high performance time-and-frequency synchronizer design, especially for DBV-T/H receiver. in order to achieve high precision of time and frequency synchronization. first stage is in time domain and then in frequancy domain. synchronization in the time domain is performed by exploiting the cyclic prefix(CP) of DVB-T/H OFDM frame structure. synchronization in frequency domain is performed by exploiting the cintinual and scattered pilot of DVB frame structure. similation results shows that proposed sychcronizer can achieve carrier frequency estimation with an error smaller than 1% of subcarrier spacing. the proposed design has also been verified in Gaussianm Rician, and Rayleigh Channel.