In current market competition, the cycles of product life are becoming short, the demands show their high uncertainty and product values decline drastically. The price protection policy in channel coordination was analyzed. The optimal price protection rate policy dynamic model of the two-period is proposed by the single ordering. The result shows that, through setting reasonable the wholesale price and the price protection rate, optimal order quantity by the retailer can be achieved. The policy optimizes the total benefit of channel alliance is optimized by the policy to obtain the win-win pattern, and finally realize channel coordination.