To better understand and estimate the secondary productivity of macrobenthos in estuary ecosystems and island ecosystems, we conducted investigations on the macrobenthos in two typical coastal ecosystems, Oujiang River estuary and Dongtou Islands, in the Eastern China sea, in April and October 2015. In Oujiang River estuary, 81 species were found, including 39 polychaete species, 23 crustacean species, 9 mollusk species, 4 echinodermata species, and 6 other species. In Dongtou Islands, 111 species were found, including 50 polychaete species, 30 crustacean species, 18 mollusk species, 5 echinodermata species, and 8 other species. Three different empirical formulas were applied to calculate the secondary productivity of these macrobenthos. The relationships between the secondary productivity and environmental factors were also analyzed. The results showed that: (1) The average annual secondary productivity of macrobenthos, measured as ash-free dry weight and calculated using three empirical formulas, i.e., Brey's empirical formula (1990) and Brey's empirical models (2001 and 2012), were 0.48, 0.51, and 0.25 g m^-2 a^-1, respectively, in the Oujiang River estuary and 0.70, 1.55, and 0.99 g m^-2 a^-1, respectively, in the Dongtou Islands. (2) The spatial distribution of the average annual secondary productivity estimated by the three empirical formulas was consistent. A zone with high average annual secondary productivity of macrobenthos was found in the southern waters of the Oujiang River estuary. Two such zones were found in the Dongtou Islands, one located in the sea area between Sanpan Island and Huagang Island, northeast of the main island of Dongtou, and the other in the sea area between the islands southeast of the Donghuang Island. (3) Six species, Aglaophamus dibranchis, Glycera chirori, Heteromastus filiformis, Potamocorbula ustulata, Yoldia similis, and Eocylichna braunsi, mainly contributed-more than 54.2% of the total-to the average annual secondary productivity of macrobenthos, in the Oujiang River estuary. In the Dongtou Islands, A. dibranchis, H. filiformis, Y. similis, Raphidopus ciliatus, Eucrate crenata, Cerebratulina sp., and Odontamblyopus rubicundus contributed the most-more than 57.1% of the total-to the average annual secondary productivity of macrobenthos. (4) Correlation analysis indicated that chemical oxygen demand, suspended solids, and median size of surface sediments were the important environmental factors affecting the average annual secondary productivity of macrobenthos in the Oujiang River estuary. In contrast, environmental factors had no measurable impact on the average annual secondary productivity of macrobenthos in the Dongtou Islands. (5) The average annual secondary productivity of macrobenthos estimated by Brey's empirical formula (1990) was consistent with that estimated by Brey's empirical model (2001), for the Oujiang River estuary, and with that estimated by Brey's empirical model (2012), for the Dongtou Islands.