This thesis is based on the comparative study of the historical documents in Portuguese, Chinese and English. These documents concern the “neutral” policies that the Portuguese government of Macao adopted during the two Opium Wars. Three conclusions emerged from this study: (1) The Portuguese “neutral” policies were not neutral. Before June 1840, the policy leaned to the Chinese authorities. After June 1840, it leaned to the British (and the French during the Second Opium War) authorities. (2) Despite the differences between the “neutral” policies during different periods, there were some common factors underlying the Portuguese “neutral" policies. One was the ultimate goal of the Portuguese government of Macao: to maintain the Portuguese settlement of Macao in their hands. This ultimate goal was to protect the Portuguese's national interest. (3) The finding of this thesis helped to confirm the significant role played by Macao in the history of Sino-Western relations. China had interacted successfully with the West through Macao for a long time prior to the Opium Wars. Sino-Western interactions did not begin with the First Opium War. The War only changed the pattern and manner of modern Sino-Western interactions.