A DLL with power-saving function includes a VCDL, a voltage control module, a capacitor, and a phase detector. The VCDL generates a delayed clock signal according to the voltage on the capacitor and a reference clock signal. The phase detector detects phase difference between the delayed clock signal and the reference clock signal and accordingly controls the voltage controller. The voltage controller sinks or sources current to the capacitor for adjusting the voltage on the capacitor. Further, the voltage controller can turn off its charge pump according to a turned-off signal and stops sinking or sourcing current for saving power.