Sino-Western relations in the eighteenth century mainly found their expression in a particular mode of commercial transactions in Canton. The structure of the Western trade with China was based on silver and colonial products from India and the Malay archipelago, like silver, cotton, pepper, lead. These commodities were exchanged for Chinese tea, silk and porcelain by the mediation of the so-called Hong trades. As long as the trade structure was kept in balance the Westerners were able to make large profits and commercial relations remained the same. When the trade structure fell out balance through, for instance, a shortage of silver or the prohibition of opium smuggling, the Western powers resorted to force. The discontinuation of the traditional Sino-Western trade because of an imbalance in the trade structure eventually did not lead to the decline of trade, but to military conquest: the Opium War in 1840. This War enabled the Westerners, headed by the English, to revamp the structure of their trade with China on their own terms and forced the Chinese government into acceptance. Since then the process of the Western expansion into China was characterised by commercial expansion, military show of force and political control. In this essay I would like to analyze how the traditional structure of Sino-Western trade lost its equilibrium and to study the changing character of European expansion into China as a result of this imbalance during the period of 1740-1840.