Abstract: Mixed culture of abalone and sea cucumber was conducted in captivity of cement pool, five groups were set up by the sea cucumber density (0, 1, 3, 5, and 7) with the same density of abalone, which was 40 per layer of the raising cage at first, and then 25 per layer after thinning;the amounts of sea cucumber of all treatments were untouched during the whole test.Growth performances of abalone and sea cucumber were detected at 510 d.The results showed no significant correlations between the sea cucumber density and the survival rate, weight of abalone and sea cucumber in summer, and the best sea cucumber density for mixed culture was proved to be 2-3per layer of the cage in this experiment.