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.