Benthic diatoms are the principal food sources for postlarval abalone in hatcheries, and the survival and growth of postlarvae depend on species and abundance of the diatoms. However, the occurrence of diatoms grew on the plastic plates in traditional way is difficult to manage. This study aims to isolate and identify suitable diatoms for larviculture of small abalone. Unialgal cultures of diatoms were achieved, with the alga was isolated by pipette under the stereomicroscope. Twelve stock cultures were maintained in liquid medium or agar slant for a long-term storage. Diatoms were observed first under the light microscope and later by the scanning electron microscope. The morphology of plastids, cell shape and fine structure of silicate cell wall were used as the taxonomic characteristics. Eight diatoms species were identified as Achnanthes submarina, Achnanthes parvula, Cocconeis placentula var. euglypta, Navicula margalithii, Amphora exigua, Nitzschia lorenziana var. incerta, Nitzschia palea, Entomoneis alata. In addition, four diatoms were classified to genus as Achnanthes sp. and Seminavis spp.