Abstract: Abstract: Scallops are the backbone variety in the development of the aquaculture industry in China, which plays an important role in the domestic fishery economic activities. Shellfish are nutritious, delicious, and have many healthcare functions, so they have much important edibleness and economic value. However, the ability to develop processing machinery and equipments for aquatic products is relatively weak, and the scallops shelling work is usually done by hand, which leads to great labor intensity, low production efficiency, bad sanitary condition, and easy bacterial pollution, affecting the taste and quality of the product. In order to improve the quality of the deep processing of scallops, a steam scallop shelling device needs to be developed. When steam is injected into the surface of the scallop, the ardent fever of the steam makes the adductor muscle (the joint of shell and carina) retrenched in an especially short moment and separates from the shell to make the ligament stretch and the shell open.In order to obtain the optimum matching of steam parameters of the device, this paper takes Qingdao bay scallop as the experimental material, breeding age at 5 months, sea area at the Yellow Sea, and fishing time as 48 hours. Shelling effect of sensory scores was assessed based on the 3 observation indexes of organization state, shell opening and the slotting degree by different groups with 8 persons as a group. Twenty bay scallops were assessed under each parameter. First, regard the shelling effect of sensory scores as the target to conduct a single factor experiment. When the intensity of pressure of steam is controlled in the range of 0.3-0.4 MPa, temperature controlled in the range of 142.92-151.11℃, and 6mm ball valves, the three best parameters optimal ranges of steam injection time A, steam injection distance B, and steam displacement C are determined: spraying time A takes 2-4 s, injection distance B takes 30-50 mm, and valve opening of steam displacement C takes 60°-90°. Furthermore, the scallop shelling test was conducted with the Box-Behnken design experimental methods, adopting the analytical method of response surface optimization, which establishes a mathematic model between the shelling effect of sensory scores and the steam injection time, distance, and displacement. The results showed that when the intensity of the pressure of the steam generator is controlled in the range of 0.3-0.4 MPa, the temperature 142.92-151.11℃ and 6 mm ball valve, and injection time is set to 3.5 s, injection distance to 30mm, and the displacement of the valve opening degree of the steam to 90 °, the scallop shelling rate is 98%, the sensory scores of the shelling effect is 94.53 points, and the shelling rate and carina quality improved significantly. Through experimental analysis, theoretical conclusions can be drawn: if the steam temperature and intensity of pressure reaches certain conditions, with larger steam displacement, shorter injection distance, and shorter injection time, the results showed better shelling effects and higher shelling rates. The research results raise appropriate shelling methods with steam, providing reference for the design of processing equipments of scallops.