Abstract: In order to clarify the status quo of water quality in Zhonglu Island ecoaquaculture area in the East China Sea, a water quality survey was launched in June, 2017. The results show that the maximal levels of NH⁺₄-N, total NO^-₂-N and NO^-₃-N, PO^3-₄-P, pH, salinity and temperature in Zhonglu Island sea area are 0.395±0.011 mg/dm³, 0.016±0.001 mg/dm³, 0.029±0.000 mg/dm³, 8.21±0.00, 32.53±0.05 and 25.07±0.16℃, respectively. The selection of improved Nemerow index for evaluation of water quality in the sea area shows that the overall water quality is relatively clean, and the distribution of water quality in the inner water differs significantly (p<0.05) in different locations. There are obvious subblocks, which may be caused by aquaculture activities. Permutation test on the improved Nemerow index by ANOVA between the water layers indicates that the difference in the improved Nemerow index is not significant（p＞0.05). It suggests that the vertical exchange capacity of the water body is strong and favors the exchange of nutrients in the bottom and the growth of natural food organisms.