Abstract: Many kinds of modern geo-hazards are closely related to the active tectonic movement since Pleistocene.Many quantitative researches have been devoted to the active tectonics on land, but seldom in the sea. This paper presents a review on progresses of the research on marine active tectonics in China and some other countries, in which, we made a review of the main problems encountered recently in quantitative studies of active tectonics in the sea area of China, and discussed the main methods for study of marine active tectonics, as well as the key issues for quantitative research and solutions based on the practice in recent years. Emphasis is put on the research schemes for the quantitative risk assessment on potential earthquake in the tectonically active region. Further, the paper discussed the way of thinking for quantitative risk assessment of marine active tectonics from self-factors of China seas.