Abstract: The exterior morphology and interior structure of Daphniopsis tibetana Sars were observed and redescribed in detail. The morphology of summer eggs, rest eggs, sperm, shell gland, antenna gland of larvae, cervical respiration organ and sense organ were reported first. The results indicated that Daphniopsis tibetana Sars and Daphnia tibetana were two different species because of their own morphylogy. Daphniopsis tibetana Sars has no carapace spine while Daphnia tibetana has postcarapace spine.