A passive auxiliary network consisting of capacitors and inductors can be added to the conventional phase-shifted full-bridge (FB) converter to achieve zero-voltage switching for all primary switches in the whole load range. Meanwhile, accurate loss analysis facilitates the proposal of novel methods to reduce losses, optimisation of converter topology and improvement of the efficiency. In this study, the detailed loss analysis of FB converters with auxiliary networks is performed, and a novel simplified loss analysis model is given. Based on the loss model, the losses of FB converter with p-type auxiliary network and Y-type auxiliary network are studied and compared thoroughly. Finally, the analytical research is verified experimentally.