The invention provides a safe starting system of a power supply, which comprises a switching circuit, a discharging circuit and a soft starting circuit. A switch circuit is connected between the powersupply and the external equipment, a discharge circuit is connected with the power supply and the switching circuit, and a soft start circuit is connected with the switching circuit and the externalequipment. A switch circuit comprises a first switch tube and a second switch tube; The first switch tube is connected with the power supply, the discharge circuit and the soft start circuit, and thesecond switch tube is connected with the discharge circuit and the external equipment. When the input voltage of the power supply reaches the turn-on voltage of the discharge circuit, the discharge circuit controls the first switch tube and the second switch tube to be turned on in the preset first delay time so that the external equipment is discharged through the second switch tube. After the first delay time, the discharge circuit controls the first switch tube and the second switch tube to be turned off. After the preset second delay time, the soft start circuit controls the third switch transistor to turn on gradually, so that the power supply can supply power to the external equipment gradually.