Semi-intensive prawn farming is currently facing difficulties in both the production and consumption processes. Climate change and an unstable output market are the main causes affecting the investment efficiency of semi-intensive prawn farming. The authors carry out the study to evaluate the financial efficiency of semi-intensive prawn farming in My Xuyen District, Soc Trang Province. Research data are collected from 100 households raising prawns. The research results show that, with an average investment cost of 19.8 million VND/1000m2/crop, farmers may earn a profit of 6.5 million VND/1000m2/crop, and the profit margin achieved reaches 0.25 times. Therefore, the model of semi-intensive prawns achieves high financial efficiency and brings a great income for prawn farmers.