Abstract: 【Objective/Meaning】The level and structure of agricultural trade between South Pacific island countries and Japan were explored in this paper and the characteristics and trends of their dynamic growth were studied, thus to promote the economic development of South Pacific island countries under the background of “One Belt And One Road” initiative.【Methods/Procedures】By using UN Comtrade, the indexes such as index, modified index, Aquino index, Brǜlhart marginal intra-industry trade index, and horizontal and vertical intra-industry trade index were selected to empirically analyze the level and structure of intra-industry trade between the five South Pacific island countries(Fiji, Papua New Guinea, Samoa, Tonga, and Vanuatu) and Japan from 2004 to 2018. 【Results/Conclusions】It was concluded that the trade between the five island countries and Japan was mainly the vertical inter-industry trade, which belonged to the complementary type, and the trade fluctuation between the two sides was mostly caused by the inter-industry trade. It was pointed out that Japan should strengthen the competition and cooperation of agricultural products with the five island countries, increase its investment and technical assistance in fisheries to the five island countries to help them increase their gains from trade.