Abstract: Bioluminescent seas caused by blooms of the dinoflagellate Noctiluca scintillans are a famous scenic attraction in the Matsu archipelago near the Chinese coast in the northern part of the Taiwan Strait. The relationship between the abundance of N. scintillans and various environmental factors was examined in the subtropical coastal waters of these islands from April to December, 2016. N. scintillans disappeared after June 20th, when the sea water temperature exceeded 27 °C. A strong inverse correlation between N. scintillans and diatoms in PCA analysis indicated that diatoms suffer high grazing pressure from N. scintillans. N. scintillans appeared most abundantly during the flood season, when diatoms are most abundant. Strong inverse correlations between N. scintillans and the wind speed and wind direction in PCA further point to the effect of wind on the accumulation of cells.