The experiment was conducted to investigate the effects of dosage and treatments of Enteromorpha prolifera on growth, digestibility, digestive enzymes and non-specific immunity enzymes of juvenile sea cucumber(Apostichopus japonicus Selenka).Juvenile sea cucumbers with the initial weight of(1.44±0.01)g were fed with 6 practical diets according to a single factor design:a basal diet contained 0, 5%, 10%, 15%, 20% and 25% E.prolifera for 49 days firstly, and then juvenile sea cucumber with the initial weight of(4.58±0.23)g were fed with 3 practical diets according to a single factor design:the diet contained 20% three treatments[dry crushing(DC), dry crushing after cellulase treatment(DCC)and dry crushing after protease treatment(DCP)]disposal(Wrong word)of E.proliferat for 60 days.There were 3 replicates per group with 35 sea cucumbers.The experiment results showed as follows:1)E.prolifera had significant influence on enhancing specific growth rate(SGR), the amylase(AMS)and the superoxide dismutase(SOD)in gut of sea cucumber and reducing feed conversion ratio(FCR)(P<0.05), and 20% E.prolifera were the best.The apparent digestibility coefficient of dry matter(ADCd)and apparent digestibility coefficient of crude protein(ADCp)of diets were significantly declined with the increasing level of E.prolifera(P<0.05).The different contents of E.prolifera had no significance on feed intake(FI), survival rate(SR), the pepsin(PP)and acid phosphatase(ACP)in gut of sea cucumber(P>0.05).2)E.prolifera with DCC and DCP had significant influence on enhancing SGR, ADCd, ADCp, AMS, PP, SOD and ACP in gut of sea cucumber and reducing FCR of sea cucumbers(P<0.05), and E.prolifera with DCC were the best.Three treatment of E.prolifera had no significant influence on FI and SR(P>0.05).Under the conditions of this experiment, the optimal content of E.prolifera in the diets of juvenile sea cucumber is 20%.And E.prolifera with drying crush after cellulase treatment is an ideal way to deal with E.prolifera.