A phase shift control method for a charging circuit, wherein the charging circuit comprises a primary conversion circuit, a first secondary conversion circuit, a second secondary conversion circuit, and a transformer connecting the three circuits, wherein the primary conversion circuit has a first group of power switches (Q1, Q4) and a second group of power switches (Q2, Q3), and the two groups of power switches have opposite switching actions; the first secondary conversion circuit has a third group of power switches (Q5, Q8) and a fourth group of power switches (Q6, Q7), and the two groups of power switches have opposite switching actions; a first capacitor, a first inductor, and a primary winding of the transformer, are connected in series between the first group of power switches and the second group of power switches; and wherein the charging circuit further comprises a first secondary current collector and a first secondary voltage collector for collecting parameters of the first secondary conversion circuit, as well as a controller connecting all the collectors and all the power switches; the controller carries out PWM control on the first and the second groups of power switches in the primary conversion circuit and also carries out PWM control on the third and the fourth groups of power switches in the first secondary conversion circuit at the same time, and further causes a phase angle difference (Φ) between an ON/OFF waveform of the first group of power switches and an ON/OFF waveform of the third group of power switches; characterized in that the controller receives an output current and an output voltage of the first secondary conversion circuit, collected by the first secondary current collector and the first secondary voltage collector, carries out comparison and calculation between the collected output current and output voltage and a preset output current and output voltage, and adjusts the magnitude and positive and negative of the phase angle difference (Φ) according to the comparison result; the controller compares and compensates the collected output current and output voltage of the first secondary conversion circuit, and generates the phase angle difference (Φ) by using the obtained compensation values, and the sum of the PWM time of the first group of power switches (Q1, Q4) and the phase angle difference (Φ) is the PWM time of the third group of power switches (Q5, Q8); and the comparison and compensation comprises: performing a difference operation between the output current of the first secondary conversion circuit and a first reference value (Iref1), performing loop compensation on the difference between the output current and the first reference value, carrying out a minimum operation on the obtained compensated value and a preset voltage loop value (Vset1) to take its minimum value as the voltage loop reference value (Vref1), performing a difference operation between the output voltage of the first secondary conversion circuit and the voltage loop reference value, and performing loop compensation on the difference between the output voltage and the voltage loop reference value, and generating the phase angle difference (Φ) by using the obtained compensation value. the controller carries out PWM control on the first and the second groups of power switches in the primary conversion circuit and also carries out PWM control on the third and the fourth groups of power switches in the first secondary conversion circuit at the same time, and further causes a phase angle difference (Φ) between an ON/OFF waveform of the first group of power switches and an ON/OFF waveform of the third group of power switches; characterized in that the controller receives an output current and an output voltage of the first secondary conversion circuit, collected by the first secondary current collector and the first secondary voltage collector, carries out comparison and calculation between the collected output current and output voltage and a preset output current and output voltage, and adjusts the magnitude and positive and negative of the phase angle difference (Φ) according to the comparison result; the controller compares and compensates the collected output current and output voltage of the first secondary conversion circuit, and generates the phase angle difference (Φ) by using the obtained compensation values, and the sum of the PWM time of the first group of power switches (Q1, Q4) and the phase angle difference (Φ) is the PWM time of the third group of power switches (Q5, Q8); and the comparison and compensation comprises: performing a difference operation between the output current of the first secondary conversion circuit and a first reference value (Iref1), performing loop compensation on the difference between the output current and the first reference value, carrying out a minimum operation on the obtained compensated value and a preset voltage loop value (Vset1) to take its minimum value as the voltage loop reference value (Vref1), performing a difference operation between the output voltage of the first secondary conversion circuit and the voltage loop reference value, and performing loop compensation on the difference between the output voltage and the voltage loop reference value, and generating the phase angle difference (Φ) by using the obtained compensation value.