Abstract: This paper presents the observation on the larval development of Portunus trituberculatus under artificial cultivation.Based on the morphological characteristics, the whole process of metamorphosis may be devided into five stages that is, four zoeal stages and one megalopa stage.The number of the feathery setae on the distal potion of the exopodites of the lst and and magillped; the form of the pleopods and the number of the setaes on the caudal concavity may be used as the main features for distinguishing the different zoeal stages.Development from the 1st zoeal stage to the young crab required 15-18 days(the zoeal stage reqired 10-12 day and the megalopa stage required 5-6 days) at the tem-perature 22--25℃ under artifical cultivation.