International trade is a set of actions that aim to exchange capital, goods, and services between foreign countries across their international borders. International trade policy is a policy related to trading across national boundaries aiming to protect the best interests of their citizens and companies. This article mainly focus on investigating of primary determinants of the international trade policy within a country. This paper summarizes the determinants by reviewing previous articles discussing Britain's international trade policy and analysing the development and advantages of protectionism and free trade policies. This research concludes that globalization has been an indispensable portion existing in international trade system, the free trade policy takes advantage of the global trend; However, considering the historical and political aspects in terms of the international trade, some inevitable past events and political decisions furtherly affect the movement of trade policy. Thus, if the government is reducing the political and historical effects when deciding international trade policies, the tendency of globalization will drive the world into a more connected place.