The same user registers accounts on different social platforms, which makes user data scattered across multiple platforms, and these data are incomplete, unreliable and low utilization. By using these cross-platform data to discover the real identity of the same user corresponding to different accounts, cross-platform user identity association plays an important role in building detailed user profiles, recommendation systems, cross-social network link prediction and other cross-platform applications. Starting from the research status of identity association technology at home and abroad, the framework of user identity association and analysis is introduced, and the standards of identity data acquisition and social network data sets are collated. Subsequently, the technology of user identity association in recent years is analyzed and the evaluation index of identity association is summarized, and the social network data mining and analysis based on identity association is expounded. Finally, the research difficulties and hotspots of identity association are discussed and prospected.