Keyword has emerging as a promising pattern for data outsourcing and high-quality data services. However, concerns of sensitive information on potentially cause privacy problems. Data encryption protects data security to some extent, but at the cost of compromised efficiency. Searchable Symmetric Encryption (SSE) allows retrieval of encrypted data. In this paper, the authors focus on addressing data privacy issues using SSE. For the first time, they formulate the privacy issue from the aspect of similarity relevance and scheme robustness.