Abstract: With the upgrading of consumption and the increase in personalized demand, unmanned retail formats have gradually become the mainstream of China’s retail industry. The development of China’s unmanned retail industry is taken as the background, and a retail firm’s decision to replenish the vending machine is taken as a case to explore the problem of multi-product joint replenishment of the vending machine in the unmanned retail industry. The results show that companies tend to replenish when there are fewer products left. The remaining products are often the smallest projected area so that the same area can accommodate the largest number of products. Comparing the optimal replenishment time with the average replenishment cost found that extending the replenishment time can reduce the average replenishment cost. At the same time, it was found that when the replenishment threshold is larger, the fixed replenishment cost is lower, or the vending machine capacity is smaller, the optimal replenishment time will decrease, and when the replenishment threshold, fixed replenishment cost or vending machine capacity increases, the average replenishment costs will increase. Analyzing the impact of different cost changes on average costs, it is found that changes in unit costs will cause an increase in average replenishment costs. When the unit inventory holding cost changes, the optimal replenishment strategy will shift to products with a unit inventory holding cost reduced to a certain degree or to the product with the lowest projected area, that is, the smallest amount that can be accommodated in the same area. Through the research, it can provide a reference for the firm to select the product type of the vending machine, and provide a decision reference for the firm to determine the optimal replenishment time and quantity.

Key words: unmanned retail; vending machine; joint replenishment strategy; replenishment threshold