Abstract: Impulse radio-ultra wideband(IR-UWB) communication systems use sub-nano second pulses for information transmission.Its synchronization method is different from the traditional system especially in frequency synchronization due to carrier-less work mode.A quasi-adaptive frequency synchronous mechanism based on an orthogonal sinusoidal correlation receiver is proposed.Phase gap is estimated by the correlation results from the local oscillator and received pulses,and the receiver changes the frequency of the local oscillator with different preset steps based on the phase quadrant obtained from estimation.Experiments show that quick synchronization and good performance are achieved with this simple algorithm.