This study trics to set up a simultancous equation model to measure the cause-and-effect of the market Structure, anduct and perforonance of Taiwanese fruit-import industry. Based on the emprical resulis, it is to identify the sources of profitability, The results, in general, have indicated that the profitability of this industry is caused most by firm's monopoly power than by its operational efficiency. However, the effects of firms' operational efficiency on their profitabilities are still important. The evidences for these results show that it is not always true since the excess porfits for some firms are treated as the consequences of their monopoly power only.