Phytoplankton communities as well as planktonic ecosystem are changing under global climate change(e.g.,warming) and human activities in the low latitude marginal seas.Such changes profoundly affect the whole ecosystem structure and functioning. In this paper,the variations of phytoplankton communities in three typical low latitude marginal seas,the Caribbean Sea,the Arabian Sea,and the South China Sea,were reviewed.The driving factors for these various changes and their correlations with global climate changes were described.The effects of community changes on ecosystem functioning were discussed.The review finally pointed out the deficiencies and future directions of phytoplankton ecology and global changes.The authors highly suggested launching a longterm observation of planktonic ecosystem structure and functioning,and elucidated the underlying mechanism of ecosystem response to climate change and human perturbation in the low latitude marginal seas.