XRD, TEM, SEM and EDS are employed toanalyze smectites in the clay fraction of the surface sedi-ments from the East Pacific. It is shown from the XRD re-sults that the clay fraction consists of ahout 20% smectites.Three types of smectites are identified, Fe-rich (Type Ⅰ ), Fe,Mg-rich (Type Ⅱ) and Na,Ca smectite (Type Ⅲ), and mostof them are not well-crystallized. Type I is widely distrib-uted in sediments, showing honeyconlblike in the SEM, andaggregated or dispersive hairlike, or cloudy assemblage witha bit curl near its edge in the TEM. This type is considered tobe typomorphic type of authigenic smectite in the East Pa-cific. Type Ⅱ is similar to Type Ⅰ in micromorphology in theTEM, showing a transition micronite, while Type III is ta-blellike in the TEM with an unclear edge. Type I may bealtered from volcanics and some of them even precipitatedfrom the low subthermal water. Type II could also be form-ed in the ocean floor, while Type III comes from dry anddistant continental area. This study suggests that the char-acteristic of chemical composition and morphology of smec-tite may give a clue to understand sediment source, origin ofminerals and sedimentation in the deep sea. XRD, TEM, SEM and EDS are employed to analyze smectites in the clay fraction of the surface sediments from the East Pacific. It is shown from the XRD re-sults that the clay fraction consists of ahout 20% smectites. Thh types of smectites are identified, Fe-rich (Type I), Fe, Mg-rich (Type II) and Na, Ca smectite (Type III), and mostof them are not well-crystallized. Type I is widely distrib- uted in sediments, showing honeyconlblike in the SEM, andaggregated or dispersive hairlike, or cloudy assemblage witha bit curl near its edge in the TEM. This type is considered to be typomorphic type of authigenic smectite in the East Pa-cific. Type II is similar to Type I in micromorphology in theTEM, showing a transition micronite, while Type III is ta-blellike in the TEM with an unclear edge. Type I could be be formed from volcanics and some of them even precipitatedfrom the low subthermal water. Type II could also be form-ed in the ocean floor, while Type III comes from dry and distant continent al area. This study suggests that the char-acteristic of chemical composition and morphology of smec-tite may give a clue to understand sediment source, origin of minerals and sedimentation in the deep sea.