Primary productivity in the western tropical Pacific and equatorial warm waters was studied in the WOCE cruise in November of 1991 and the TOGA-COARE cruise from November of 1992 to February of 1993.It is shown that the total amount of integrated chlorophyll a (chloro.a) was 19.79mg/m2 in depth of 0~150 m and the average daily primary productivity was 171 mg/(m2·d) (C)appeared in the western tropical Pacific while a higher chloro, a (21.68 mg/m2) and primary productiv ity[228 mg/(m2·d) (C)] were observed in the equatorial warm waters.The highest chloro.a was found at the coastal stations of Philippines and Irian while the lowest chloro, a was at the offshore areas bounded by 2°~4°N.The distribution pattern of chloro, a biomass was related to different physical processes.Upwelling, which may have led to a high biomass, was a critical factor changing the distributions of temperature, salinity and nutrient in these areas.