The paper models the effect of the energy-saving subsidy for a firm and consumers with a three-stage game． The aim is to design the optimal subsidy contract for improving the energy-saving attribute per product and total energy-saving attribute respectively． Moreover，this paper studies the optimal energy subsidy contract’s effect on the firm’s profit and consumer surplus． Here are two main results: When the government invests rarely，the optimal energy-saving subsidy contracts under the two objectives are the same，and the consumers and thefirm obtain no improvement from them; When the government aims to improve the total energysaving attribute and its investment is sufficiently large，the firm’s profit and the consumer surplus increases under the optimal contract the government adopts．