Abstract: According to the data collected from drilling holes and tidal current observations, using numerical simulation methods, the environmental capacity for sea sand mining is studied in the eastern Liaodong Bay. The average thickness of the sand layer ranges between 4.0~6.0 m. The total reserve of sand is about 3818×10⁴m³. The sand content is generally in the range of 84.4%~92.4%. The results of simulation indicates that the suspended mater caused by sand mining is less than 10 mg/L and mainly spread in the experimental area of the germplasm resources conservation area and the Natural Reserve of Spotted Seal of the Liaodong Bay. However, the suspended sediment has no severe impact on the core area of the above two experimental areas. After the mining of marine sands, the erosion rate will decrease in an amount of 0.002~0.02 m/a in the subbottom pipeline section, even though it may increase by 0.001~0.005 m/a in some areas. But in general sand mining will not have influence on the pipeline. The erosion and deposition rate is less than 0.001m/a in the eastern beach. It is suggested that the mining depth, mining area and mining amount and intensity should be controlled, and in-situ monitoring and other measures should be enforced to mitigate the impact of sea sand mining activities on the marine environment.