Diatom plays a significant role in the carbon cycle of the whole world.Thriving to mats in the subsurface water, the “shade flora” is buried rapidly and becomes diatom mat deposits. The subsurface diatom production plays a considerable role in the whole productivity and output productivity. The distribution of diatom mat deposits discovered in the west low-latitude Pacific Ocean is introduced in this paper. The occurrence of diatom mat deposits in the west low-latitude PacificOcean in the last glacial period makes this area become the sink of CO2 probably.