In order to improve the traditional phase-shifting full bridge converter circuit which is difficult to meet the demand for soft switching under half load under high power and wide range of output voltage,and the problem of high circuit loss,we have designed a new phaseshifting full bridge converter circuit,that is,the auxiliary current source network is connected in parallel on the lagging leg,which is the most difficult to achieve soft switching,so that change the operating mode of phase-shifting full bridge circuit and the lagging bridge arm can still achieve soft switching under a wide range of load,while reducing circuit loss.The simulation and loss analysis of the designed circuit prove show that the new phase-shift full-bridge circuit can meet the soft switching requirements of 19%～100%of the rated load at the output voltage of 77~137.5V,which is about 15%higher than the traditional circuit soft switching range.Meanwhile, in the range of soft switching,the efficiency of the new phaseshifting full-bridge circuit switching device is greater than 96.3%.The rationality of the proposed design scheme is proved.