Double-clamped zero-voltage-switching buck-boost (DCZVS-BB) converter is an isolated topology with excellent zero-voltage-switching (ZVS) capability and wide input voltage range, which is widely used in high power density applications. Current researches mainly focus on operating mode 1 with smaller clamp capacitor, while operating mode 2 with larger clamp capacitor has not been discussed in detail yet. In this paper, the steady-state characteristics and ZVS condition of the DCZVS-BB converter operating in mode 2 are analyzed. A detailed power loss model consisting of switching loss, conduction loss and transformer loss is established, then a control method to minimize power loss is proposed by optimizing the control variables. Compared with conventional control methods, the proposed method can achieve precise magnetizing current control for efficiency improvement without look-up table. Finally, the effectiveness of the proposed control method is verified by a prototype with the switching frequency of 200 kHz.