Now big data has become a hot topic in academia and industry, it is affecting the mode of thinking and working, daily life. But there are many security risks in data collection, storage and use. Privacy leakage caused serious problems to the user; false data will lead to error results of big data analysis. This paper first introduces the security problems faced by big data, analyzes the causes of privacy problems, and discusses the principle to solve the problem. Finally, discusses technical means for privacy protection.