Trade surplus studies the development of a country's foreign trade, mainly with the help of the foreign trade balance table published by the government on a regular basis. Generally speaking, the balance sheet contains statistical data showing exports and imports systematically, which can generally reflect a country's foreign trade and even national economic development in a specific period. A country's foreign trade constitutes a trade surplus, a trade deficit or a trade balance according to the situation that exports are greater than, less than or equal to imports.

1. Trade surplus. The so-called trade surplus means that the total export trade of a country is greater than the total import trade in a particular year, which is also called surplus. This shows that the country's foreign trade was in a favorable position that year. The size of the trade surplus largely reflects a country's foreign trade activities in a specific year. Under normal circumstances, it is not appropriate for a country to maintain a large foreign trade surplus for a long time, because it is easy to cause friction with relevant trading partners. For example, one of the main reasons for the market fluctuation of bilateral relations between the United States and Japan is that Japan has been in a huge surplus for a long time. At the same time, a large amount of foreign exchange surplus usually leads to the increase of local currency in a country's market, which is easy to cause inflationary pressure and is not conducive to the sustained and healthy development of the national economy.