Aiming at the challenge of DC bus voltage stability in AC/DC hybrid power supply system of data center, this paper proposes a control strategy based on single phase bidirectional converter. The strategy takes data center as the application scenario, adopts the backstepping control design, realizes the large signal control by constructing the virtual quantity, improves the control precision and stability of DC bus voltage. At the same time, an on-line load estimation method with adaptive control law is proposed, which realizes the advance regulation of bus voltage and enhances the dynamic response ability of the system. The simulation results show that this strategy can significantly suppress voltage fluctuations and improve the steady-state control accuracy to less than 0.2% without increasing the DC bus capacitance, which has important engineering value for improving the system reliability.