Abstract: Investigations on chlorophyll a and environmental factors were carried out in Minjiang Estuary of Fujian, from March to December 2008. The chl- a concentration ranged from 0.25 to 45.38 μg/L with a mean value of 3.93 μg/L. The chl-a concentration horizontal distribution in spring and summer were descending from the sea area near Langqi Island to east of Chuanshi Island and inner Dinghai bay, while was even in autumn and winter . With regard to seasonal variation, chl-a concentration was the highest in summer, followed by autumn, spring and winter in sequence. Correlation analysis showed a significant positive correlation between chl-a concentration and water temperature, and a negative correlation between chl-a concentration and salinity, phosphate.