清康熙二十三年，即西元1684年，在台灣內屬之後，清廷開放中國沿海的海上貿易，同時也准許中國帆船往來台灣從事商業、漁業活動。在清領之前，台灣與日本及東南亞之間原有海路貿易的存在，清領之後，這樣的貿易也維持了一段期間，但從某一不易確定的年代開始，本島與中國以外地區的商業活動就不復存續，只有兩岸之間的帆船貿易與本島的環島貿易依舊有所發展而已

This paper aims at discussing the changing trend of the trade between Taiwan and the Chinese mainland as carried on board the junks. Due to difficulties in estimating the value and quantity of merchandises involved in the trade, this paper tries to make an estmation on the shipping capacities of the junks employed in the trade. In terms of varieties, the staple exports of Taiwan (rice, sugar, peanut oil and indigo, especially the first two items) did not undergo significant change in the period under iscussion, while the scale of the import trade was heavily dependent on that of the export trade. In consequence, an estimation of the total carrying capacity is also possible to reflect the general situation of the whole trade. Our estimation has the following findings. In the late 1780s, when Lu-erh-men, Lu-kang and Pa-li-fen were opened for legal trade, the total weight of merchandises annually brought out from Taiwan was something between 1,900,000 and 2,250,000 shih (about 133,000 to 157,500 tons). The number went down to something between 500,000 and 600,000 shih (about 35,000 to 42,000 tons) previous to the outbreak of the Opuim War (1840~42). Such a downward movement of the trading trend was mostly contributed by the decline of the junk shipping of Lu-erh0men and Lu-kang, while Pa-li-fen remained relatively steady.