The present invention discloses a multiphase waveform generator capable of performing phase calibration, and a related phase calibration method. The disclosed multiphase waveform generator includes a multiphase waveform generating module and a calibrating module. The multiphase waveform generating module receives an input signal and shifts edges of the input signal by a delay time according to a delay parameter to generate a phase-modified signal. The calibrating module is coupled to the multiphase waveform generating module for calibrating the delay time to reduce a difference between a characteristic value of the phase-modified signal and an expected value, which is calculated according to the delay parameter and characteristic values of a first and a second predetermined periodic signal.
