With household disposable income increase, the proportion of food away from home (FAFH) consumption rises rapidly in the total household food consumption. Consumer s plate waste has attracted increasing public, academic, and political attention in recent years. In order to understand the reason that cause plate clearly, this empirical study sheds light on the effect of preference for food variety and average portion size on the plate waste using survey data from 1340 tables of 161 restaurants in Beijing and Lhasa. The key finding suggests that income increase leads more preference for food variety when consumer dining out; and we verify that a consumer is more likely to waste food when variety preference increase by using dining reason as an instrument and average portion size of restaurant increase. Our result implys that the restaurant should reduce the average portion size of dish with residents' income increases, which can reduce the consumer s plate waste. This paper introduces the preference for food variety into the utility function, which makes the utility function of residents FAFH more perfect and more realistic, and we introduce an order decision into the analysis framework, which constitutes a two-step decision to plate waste. Acknowledgement :