A loss-averse retailer game with random demand and yield is studied. When multiple identical retailers order from a single supplier, the total demand is allocated among the retailers proportional to their order quantities. Then there exists a symmetric Nash equilibrium in this game and it is unique. The total equilibrium order quantity is decreasing in the loss aversion level, while increasing in the number of retailers. Moreover, there exists a threshold of loss aversion level (number of retailers), above (below) which the total inventory level of a competitive supply chain is lower than that of a centralized one. The numerical experiments are conducted to demonstrate the above theoretical results.