Objective To further articulate the conceptual framework of sub-health by way of literature review. Methods Published papers and relevant literature about sub-health were collected, the representative publishing about theoretical exploration and practical surveys were focused for analyzing and assessing the category of sub-health, investigative objects, assessing tools, conceptual framework, diagnostic criteria and its operability, foundation support, etc. Results Sub-health conditions were categorized into three kinds in most documents, namely, the somatic, the mental and the social adaptative sub-health, and the relevant symptoms were classified into three levels. However, contents regarding the homogeneous issues, such as meaning and definition of sub-health, its diagnostic criteria and operability, in different documents were discrepant. Conclusion Discrepancy exists between the theoretical and practical studies of sub-health. And detailed description is needed to articulate the problems respectively on specific and non-specific sub-health. The perspicuity of conceptual framework is the basis of sub-health researches. The authors recommended that to form the framework the four-level hierarchic structure should be adopted; in developing the assessing tool for sub-health diagnosis, besides the basic assessment on concrete conditions, the differential evaluation on the belonging of overall manifestations, subjective complain or objective symptom, should also be paid attention to.