With rapid e-commerce development, more and more physical retailers set up online sales channels. Based on the data of 47 Chinese listed retailing enterprises from 2001 to 2017, this paper uses the Difference-in-difference Model to test the impact of the added online channels to the inventory/income ratio and fixed asset/income ratio. The results show, first the added online channel can reduce 12% inventory/income ratio significantly, which means the Internet can improve the operational efficiency of retailer. This effect continually increases with time. Meanwhile, the grocery retailers selling low-experience goods gain much more from online channels compared to the retailers selling high-experience goods. Second, the added online channels do not significantly reduce the fixed asset/income ratio, which means that the physical retailer develops both channels at the same time. All these results indicate that the Internet can improve the operational efficiency, and the dual channels which contain both physical and online selling outlets are an important new retailing type.