The study was conducted to assess the changes of coastal sea water quality in 2021 in Soc Trang province, Vietnam. Monitoring of coastal sea water quality was carried out with a frequency of 4 times/year at three locations NB1, NB2 and NB3. At each monitoring location, 14 parameters were collected, respectively, including temperature, pH, turbidity, salinity, conductivity (EC), suspended solids (TSS), chemical oxygen demand (BOD), mineral oil, phosphate (P-PO₄^3-), nitrate (N-NO₃^-), nitrite (N-NO₂^-), ammonium (N-NH₄⁺), iron (Fe) and coliform. The results of each monitoring parameter were compared with the National Technical Regulation on Sea Water Quality (QCVN 10-MT: 2015/BTNMT) for the purpose of aquaculture and conservation of aquatic species. The results show that the coastal water quality in Soc Trang province is still relatively good. Most of the coastal water quality monitoring parameters do not appear to be polluted. Only 2 out of 14 monitored parameters, TSS and Fe, respectively, appear to be contaminated with high concentrations. The high content of TSS and Fe in the water poses many risks of harm to aquatic organisms in the study area and costs a lot to treat before use. The cause of pollution in the coastal area of ​​Soc Trang may stem from the natural conditions of the area, influenced by the amount of surface water from the estuaries into the sea.