Whether the related party M&As has a communication advantage effect is a new topic. Based on the theoretical framework of social capital, this paper discusses the communication advantage of the related party M&As. Two dimensions are considered. They are social network and trust mechanism, the former is to increase the breadth of information source, and the latter to increase the depth of information. This paper further discusses the specific information asymmetry reduction mechanisms of the related party M&As. Results show that the related party M&As are positively related to firm performance in the sample of higher information asymmetry. No significant results are found in the sample of lower information asymmetry, which indirectly verifies the communication advantage of the related party M&As. Creating priori information and information exchange can explain the information advantage, while no evidence stands for the mechanism of professional information. This paper also proves that if shared benefits rather than private benefits dominate, the communication advantage of related party M&As will be more significant.