It is a flaw for the previous studies to neglect the horizontal competition between manufacturers. This paper analyzes how the introduction of an etailing channel to an existing retailing channel affects the payoff of itself, its channel partner (i.e. retailer in this paper) and its competitor. We found out that, for the manufacturer with an etailing channel, the product etailing market share and product substitution have positive impact on its payoff and channel substitution have negative impact on its payoff. For its competitor, the manufacturer without etailing channel, etailing market share and channel substitution have little impact on its payoff. For their common retailer, the three factors have negative impact on its payoff.