Previous research on the influencing factors of stock price co-movement，based mainly on the theory of Social Embeddedness，suggested that the information diffusion function of listed companies’social relations，such as Institutional Ownership，is one important factor． There are a large number of individual investors in Chinese stock market，where the impact of information interaction among individual investors through social media on stock price co-movement is becoming increasingly prominent． Using the data from Eastmoney， this paper investigates the impact of individual investor behavior on stock price co-movement from a more microscopic perspective，based on the Effective Information Theory and the Social Embedding Theory． The empirical results show that the higher the weight of edges in the information diffusion network，which is based on information interaction，the greater the correlation coefficient between stock prices． Furthermore，massive and frequent posts or replies by users through social media can promote the spread of stock information，thus affecting stock price co-movement． In addition，the information flow generated by individuals has a predictive effect on stock price co-movement． The above results show that stock information diffusion through individual information interaction is another important factor affecting stock price co-movement． The conclusion is helpful in deepening the understanding of the underlying causes of risk conduction in the stock market and provides theoretical guidance for risk management in Chinese stock market．