This paper investigates how manufacturers' innovation investment affect retailer's information sharing strategies in a two-echelon supply chain involving two competing manufacturers and a common retailer. Three information sharing models(i.e., no sharing, partial sharing and full sharing) are established, and the relationships of manufacturers' or the whole supply chain's profits under different strategies are obtained by comparative analysis. Then, we extend the basic model to examine how asymmetric investment efficiency and horizontal spillover impact retailer's information sharing strategies. The results show that when manufacturers' investment efficiencies are equal, if the investment efficiency is low, the retailer has no incentive to share information; if the competition between two manufacturers is less intense(intense) and the investment efficiency is high(moderate), the retailer always tends to adopt full sharing strategy; if the competition intensity is intense and the investment efficiency is high, the retailer prefers to choose partial sharing strategy. When the investment efficiency is asymmetric, the retailer is more inclined to share information with the manufacturer having higher investment efficiency. In addition, spillover effect always incentivizes the retailer to share information.