Sinonovacula constricta, with its own unique advantages, has become one of the early large-scale shellfishes in China, known as the four major cultivated shellfishes together with oysters, cockles and clams. Aquaculture of Sinonovacula constricta is a pillar industry in Fujian. However, until now Sinonovacula constricta is still harvested mostly by manual work with heavy labor intensity and low work efficiency. In response to the above problems, a kind of new-style Sinonovacula constricta harvester was developed by Fujian Agricultural and Forestry University, which innovated the harvesting method by combining the three processes including harvesting, sorting and collecting together in one working process to improve the working efficiency and reduce the labor intensity. The harvesting and cleaning unit, as the core part, was designed with the working height of 791 mm and the width of the mud inlet of 500 mm. In order to overcome the leakage of Sinonovacula constricta from the sieve holes during harvesting, the shell width, shell height and shell length were determined by the deep culture experiments on Sinonovacula constricta, and the best sieve design parameters were obtained basing on the biological characteristics of Sinonovacula constricta. The best diameters for the sieve holes shall be 10~12 mm. The unit can not only apply to the harvesting of the thin-shell shellfishes represented by Sinonovacula constricta, but also provide a reference for the development and application of harvesting devices of the thin-shell shellfishes, thus having a better development prospect.