Abstract: From the new perspective of transaction utility theory， the effect mechanism of price promotion on customers' impulsive purchase was explored. It was concluded that price promotion significantly affects customers' impulsive purchase directly or indirectly， transaction utility plays a partial mediating role between price promotion and customers' impulsive purchase， and companions' purchase proposal tendency plays a regulating role in the impact of price promotion on transaction utility， the impact of transaction utility on customers' impulsive purchase as well as the impact of price promotion on customers' impulsive purchase. It was thus suggested that such strategies as commodity comparison and companion inspiring should be applied to help enterprises or businesses to carry on more effective price promotions， enhance the transaction effectiveness of customers， and broaden the impact boundary of price promotion on customers' impulsive purchase， thereby increasing their marketing performance.

Key words: price promotion, customers' impulsive purchase, transaction utility, companions' purchase proposal tendency