Objectives: This review is aimed to figure out the effectiveness of herbal medicine for treating threatened abortion by analyzing randomized controlled trials. Methods: We searched relevant studies using seven databases including 4 domestic databases and 3 foreign databases. Data retrieval was conducted on May 18, 2022. and the papers published from January 1, 2018 to May 18, 2022 were included. The risk of bias was assessed by using Cochrane's risk of bias tool. Results: 182 studies were searched in domestic and foreign databases, and 9 studies were finally selected. Among 9 studies, the treatment group was treated with only oral herbal medicine in 4 studies and with combined treatment of herbal medicine and western medicine in 5 studies. On the other hand, the control group was treated with only western medicine. In all 9 studies, evaluation indexes in the treatment group showed more effectiveness than those of the control group, evaluation indexes were different for each study though. Conclusions: Herbal medicine was more effective for treating threatened abortion whether using it alone or combining with western medicine compared to using western medicine alone. Additional studies which include large number are needed to confirm long-term effectiveness and safety of herbal medicine treatment.