This study researched seed production technology for bivalvia soft-shell clam. The result of the experiment on the fertilized egg development showed the fertilized egg was 80.8 mm, and it took 29 hours to reach the stage of the D-shaped larvae at a water temperature of 17°C. The first feeding of larva took place 44 hours after fertilization. The D-shaped production of soft-shell clam fertilized eggs was in the range of 17-23℃ in water temperature and 30-33℃-77-78% in salt concentration. Based on the experimental results, foot was formed at shell length 231.6 ± 10.6 μm around 15 days after fertilization according to the results of mass seed production at 17.2-24.5℃, 31.2-33.6%, and landing was completed at shell length 258.4 ± 10.6 μm around 20 days after fertilization. Plantigrade larvae reached average shell length 1 mm around 44 days after seed production, and an average of 3 mm around 66 days.