The work aims to construct a British auction model to match the number of Stock Keeping Unit (SKU) to be assigned with the number of storage locations in the area to be assigned by gradually increasing the minimum turnover rate of the SKU group to be assigned as a medium. The storage location assignment method based on British auction was proposed to improve the picking efficiency in the warehouse for the storage location assignment in Robotic Mobile Fulfillment System (RMFS). Compared with the random assignment model, when the storage location assignment based on British auction was adopted in RMFS with different warehouse scales, order sizes, and order biases, the travel distance reduction rate of robot reached 30.17% in large warehouses, 27.31% in medium-sized warehouses, and 24.13% in small warehouses. The use of the British auction mechanism in RFMS for storage location assignment can significantly improve efficiency.