This paper takes Sasakawa Pacific Island Nations Fund（SPINF）as example，and gives detailed analysis on its assistance to the South Pacific Island Nations，including the reasons，modalities，fields of the aid as well as the position and function of NGOs in Japan’s foreign aid. Since the challenges that South Pacific Island Nations faced with，such as narrow anddistributedland，isolation from the international market and fragile ecological environment，it was chosen by the SPINF as key assisting area. The assistance was mainly operated by three ways，self-operated project，funding project and self-operated/commissioned project，which covered a wide range of fields including education，environment protection and climate change，medical care and so on. NGO plays an irreplaceable role of its supplementary and initiative function in Japan’s foreign aid.