Whether increasing the number of choices will improve satisfaction is a hot issue in economics, psychology and marketing. How does ambivalence affect choice overload when consumers have both positive and negative evaluations of one stimulus target? Two experimental results show that the effect of option number on satisfaction is suggested through the level of decision-making difficulty. When the option number affects the level of decision-making difficulty, choice overload will occur. Ambivalent attitude has a moderating effect on the relationship between decision-making difficulty level and satisfaction. For those with higher ambivalence, the more the better. On the contrary, for those with lower ambivalence, the product is “enough is enough”, and the increase of option number will reduce consumer satisfaction.