By 5 main methods including data collections and compilations, field surveys, similarity comparison, mapping and GIS, the geomorphological characteristic of notches in Ha Tien – Kien Luong containing morphologies, origins and ages are proved. Those notches had morphologies of U and V and 3 types of origins including chemical solution, mechanical abrasion and bioerosion; notches were formed in stage of Holocene regressive sea. Notches were created at four stopped periods corresponding to four sea level elevations: 5 m, 3 m, 1 m and 0 m (current sea level) respectively had the age of 5.480, 3.180, 1.025 years ago and the current level has being formed. This research had provided a useful scientific literature that includes the essential role of organisms in forming notches, the influences of organisms, waves and shielding rate on morphologies, and evidence of climate change in the past. By those reasons, people need to calm down, observe, adapt, and respond flexibly to the climate change instead of constructing costly structures. Coastal notches are important marine geological heritage so the conservation of those coastal notches were necessary for research and education, prediction of the sensitive Ha Tien – Kien Luong region, contribution towards risks of planning and construction in areas of underground limestone caves.