Abstract: A clock data recovery circuit includes an equalizer, a multi-phase clock generator, a sampling and check unit, a signal edge detection unit and an adjusting unit. The equalizer performs an equalization on an incoming data signal. The multi-phase clock generator generates multiple clock signals and at least one pair of check signals. The sampling and check unit samples the incoming data signal according to the clock signals to obtain a sequence, and checks whether the sequence matches a predetermined pattern. If so, the signal edge detection unit controls the sampling and check unit to detect a transition between values of the sequence two on two based on the pair of check signals to obtain a detection value. The adjusting unit determines whether the transition is too early or too late according to the detection value, and adjusts the equalization on the incoming data signal according to the determination result.