Regional cooperation is crucial to the peace and development of the Pacific region.The regional cooperation has made some progress.The paper has examined the diversity of the region in terms of historical and cultural background，geographical concept and regional organizations to come to the conclusion that the region is by nature complicated and complex.Therefore，overcoming the diverse regionalism is slow and hard.However，regional cooperation is beneficial to the development of the region.Regional cooperation should be executed with strong regional cooperation organization such as the Pacific Islands Forum and aim at an uniformed institution and markets.Also，new cooperation opportunities should be found to overcome the difficulties and push the development.