The characteristics of primary productivity, utilization of solar energy efficiency and their impact factors under the different culture models were studied in the coastal fish ponds of Jiangsu. The results showed that there existed dynamic changes of the primary productivity (such as vertical distribution, daily variation and seasonal changes) in the water of fish ponds, and thus changes were directly related to the solar radiation intensity. The average net primary productivity (Pn) was (7.58±2.52) gO2/(m2·d), which was only about 55.41% of gross primary productivity (Pg). The ecological efficiency of transforming solar radiation energy to carp products was from 0.020% to 0.029%, the ecological indexes were lower in the coast fish ponds than the high-yield ponds, indicating that the ecosystem structure needs to be further optimized. The primary productivity of the water was significantly affected by the phytoplankton chlorophyll, solar radiation intensity, phytoplankton biomass, transparency, N/P ratio, Mg2+ concentration, but not significantly influenced by the contents of total salts and concentrations of Na+ and Cl- in the water.