Massive Open Online Course (MOOCs) has helped develop the education sector since the COVID-19 pandemic, though it causes low retention. This study used a systematic literature review method to analyze the factors affecting the retention level of MOOCs participants in developing countries and worldwide. A total of 89 publications in the Scopus journal during 2015-2021 and 26 published in developing countries were examined. The results showed that the factors affecting the retention level of MOOCs' participants include perceived ease of use, usefulness, social influence, and self-efficacy. However, motivation was an insignificant factor in developing countries despite being significant worldwide. Infrastructure was an internal factor for the retention level among participants, though this study can be further expanded using better methods.