Ecosystem provides supply, regulation, support and cultural services. The value assessment of ecosystem service functions is helpful for people to understand the importance of natural ecosystems to production and life. Through analyzing domestic and foreign research on ecosystem service value, this paper sorted out the research process of value assessment. Based on the assessment process, the existing assessment methods and the introduced model methods were summarized, and the methods and models used by the latest research were classified. According to the weakness of the existing studies, it discussed prospects of future research. It is expected to promote multi-scale and multi-directional research exploration and enrich the theory and method of value assessment.