The data used in this study was based on Annual Economics Survey of Offshore Fisheries and Aquaculture in Taiwan, from 2000 to 2003. The model of stochastic frontier production function was specified and estimated. The result showed that return to scale was decressed and farmers use more fry cost, feed cost, temporary labor cost and other costs, the value of output will increase in hard clam aquaculture in Taiwan. The study suggested that hard clam aquaculture in Taiwan should raise culture density in an appropriate degree but to expand the culture scale was unsuitable.