Most of the marketing channels have the characteristics of power asymmetry, among which the power of the weakers in quantity cannot be underestimated. However, the existing research of channel power focuses on the power acquisition, influence strategy and control mechanism from the perspective of the stronger, and pays less attention to the weaker. Among these few studies on the weaker, most of them follow the perspective of taking the stronger as the enemy, and pay more attention to the defense and confrontation mechanism of the weaker, but fail to conduct in-depth research on the acceptance and cooperation behavior of the weaker to the exercise of power.

Different from previous studies, this paper chooses the perspectives of the weaker and the cooperative orientation. Based on the legitimacy theory of the observer’s perspective, this paper holds that the power legitimacy of the weaker, that is, whether the weaker’s subjective perception of the power exercise behavior of the stronger is “necessary, appropriate and appropriate”, is an important factor affecting the behavior choice of the weaker and even the channel performance variable, and focuses on the complex aspect of cooperation（compliance）and non-cooperation（opportunism）in the reaction behavior of vulnerable parties. The research objectives of this paper are as follows: First, the legitimacy of power is divided into two categories: effectiveness legitimacy and moral legitimacy. How do different types of power legitimacy affect the weaker’s choice of cooperative behavior（compliance）and non-cooperative behavior（opportunism）? Second, are there differences in the magnitude of the above effects? Third, are compliance and opportunism independent variables? How do different types of high/low compliance and opportunism affect channel performance?

Through the questionnaire survey of 283 sample enterprises, this study draws the following conclusions: First, the weaker will adjust itself（compliance or opportunism）based on the legitimacy of power, and then affect the channel performance level. Second, the influence of different legitimacy of power on the behavior of the weaker is different. The effect of actual validity on compliance is significantly stronger than that of moral legitimacy. Although this study cannot reject the original hypothesis that there is no（linear）effect on opportunistic behavior, it can prove that moral legitimacy does have a significant negative impact on opportunistic behavior. This result can reflect the asymmetric nature between the effect of effectiveness legitimacy and moral legitimacy on opportunistic behavior to a certain extent. Third, compliance and opportunism are two independent variables, and there is the possibility of “comply in public but oppose in private”, that is, the high compliance and the high opportunism coexist. In addition, the channel performance of different combinations of compliance and opportunism shows significant differences. Compared with the other two types of behavior, the channel performance of “comply in public but oppose in private” is significantly lower than that of high compliance/low opportunism behavior, and also significantly higher than that of low compliance/high opportunism behavior. This paper provides in-depth research results on the weaker’s acceptance of power and corresponding response behavior, which is helpful to provide corresponding guidance and reference for marketing channel management.