Objectives To describe the range of strategies for expanding health insurance coverage for vulnerable population and how the authors have assessed these strategies. Methods Search words were chosen by both health policy experts and search coordinators after discussion and pilot. What was searched included 28 electronic databases, 12 websites of health institutions, 3 grey literature databases and search engine Google. Any report of implemented strategies to expand health insurance coverage for vulnerable population was included. Pre-designed data extraction form was used for collecting strategies and study methods of the included studies. Then the extracted information was analyzed and described. Results A total of 86 studies were included, most of which were the ones in the U.S. and the main targeted population was children. In terms of the study objective, 61 studies aimed to describe strategies and 25 ones are to evaluate effectiveness of the strategies. All strategies could be categorized into 6 groups based on the theoretical framework: changing eligibility criteria of health insurance, increasing awareness, making premium affordable, innovating enrollment approaches, improving health care delivery and strengthening management capacity. Most of the studies evaluating effectiveness were retrospective analysis of longitude data, and there were also two experimental studies. Conclusions The U.S. and other developed countries have implemented a great many strategies for expanding insurance coverage, while few strategies and related studies are found in developing countries. However, developing countries can learn from the developed countries in extending health insurance coverage. The 25 included studies evaluating strategies need further systematic reviews to assess the effectiveness of these strategies.