Abstract: Under laboratory conditions, shrimp aquaculture effluent was treated with six densities of Gracilarla tenuistipitata var.liui (0, 10, 20, 25, 30 and 35 g·L^-1) respectively for comparing the efficiency of the degradation of NH₄⁺, NO₂^-, NO₃^-, PO₄^3- in 24 h. The obtained results showed that all of the five densities used had obvious positive effects on the degradation of NH₄⁺ and PO₄^3-(P < 0.05). The optimal density of Gracilarla tenuistipitata var.liui for degradation was 30 g·L^-1, which can result in 69.69% and 92.62% of relative rates of degradation for NH₄^- and PO₄^3-, respectively.