The sixteenth century is considered the beginning time of trade activities between Vietnam and Western countries after great geographical discoveries in the world, in which Portugal was the pioneer country to establish trade relations wit h Vietnam. Cochinchina, with many favourable factors in terms of human, geography, and goods, was the place to attract Portugal on the way of exchange and establishment of Intra - Asian marine trade network. Thus, what factors led Cochinchina to a strategic position in this trade network, and Portugal had come here to trade with specific characteristics are, and the consequences of this trade process are, is the purpose of this article. Based on analyzing objective and subjective factors, generalizing and systematizing commercial activities between Cochin china and Portugal, the author provides objective assessments of the role of Cochin china in the voyage to The East of the Western countries in the contemporary time.