Potash is an important fertilizer in agricultural production .China's potash fertilizer production is difficult to meet domestic market demand so it has to import from the international market. But the international potash market is a typical oligopolistic markets, oligarchs has a strong control over the price of potash fertilizer. It has not only brought China's potash fertilizer import trade great difficulties, but also caused a great impact for China's agricultural development. This article analysis the international potash trade from the perspective of market structure to help China take the necessary measures to ultimately improve the import trade in potash. This paper is divided into five chapters, the first is an introduction and literature review, followed by introducing the world potash trade from the perspective of market structure, and the last is the conclusion and the countermeasures. In this paper, empirical and theoretical research found the following results: First , the international potash market is high oligopoly type Ⅱ market on the national level. Canada, Russia, Belarus, Germany are the main oligopolies. Canada has the most market power, while Belarus has the highest RCA index. Second, the international potash market is also an oligopoly market on the corporate level. BPC, Canpotex, K + S and IPC are major market oligopolies. BPC and Canpotex control the supply of the international potash. Third, the international potash market is an oligopoly markert which has existed for a long time, and will not change in the long term.