Hybrid AC/DC microgrid combines the advantages of AC microgrid and DC microgrid, its optimal planning problem is a hotspot of current research. Taking into account the inverter configuration, stochastic failure of equipment, operating state of microgrid, constraints of interactive power fluctuation between submicrogrid and the fluctuation between microgrid and main grid, this paper establishes an optimal planning model in hybrid AC/DC microgrid system with wind turbine generators, photovoltaic generation and energy storage battery. In this model, mixed integer programming method is used to solve the objective function with the summation of installation cost, operation cost and reliability cost. Optimal planning is carried out under different DC load ratios and is compared with AC microgrid. The case study indicates that hybrid AC/DC microgrid has advantages in both configuration cost and reliability, and the advantages become more obvious as the change of DC load ratio. This work is supported by National High-tech R & D Program of China (863 Program) (No. 2015AA050104).