A multi-voltage power supply includes a transformer connecting to an AC power source to regulate voltage and deliver voltage-transformed electric power, a rectification output circuit connecting to the transformer to rectify the voltage-transformed electric power and output first DC power, and at least one voltage regulation circuit to receive the first DC power from a first DC power output line and regulate to become second DC power. The first DC power on the first DC power output line reaches a first potential after a voltage boosting period. The rectification output circuit has a rear end installing a hysteresis unit which adds a delay time in the voltage boosting period to defer the time of the first DC power reaching the first potential. Thereby the time difference between delivering DC power output of the first DC power and the second DC power can be regulated to avoid abnormal start of computers.