Abstract: There are many polder areas located around Chao Lake and agricultural activities are conducted in these areas. Nutritive salt exportation from polder areas is an important factor of non-point source pollution in Chao Lake. In order to understand nutritive salt export characteristics in this area, a typical polder area located on the coast of the lake was chosen for the study, systematic field survey observation, sampling and indoor water quality analysis were conducted in rice growing period in 2014, and the change of concentration and export characteristic of nutritive salt in polder areas under natural rainfall-runoff condition were discussed. There were 9 rainfall-runoff events in rice season in 2014 and the total amount was 73.09 mm, runoff coefficient was 0.37. The mean concentration of total nitrogen (TN) and total phosphorus (TP) were 3.42 and 0.22 mg/L in the 9 rainfall-runoff events, which reached the eutrophication levels. The amount of drainage played an important role in the variation of nutritive salt concentration, the export amount of TN and TP in rice growing period were 0.28 and 0.017 kg/hm², which accounted for 1.7% and 0.16% of nitrogen and phosphorus fertilization input. Volume of runoff was also an important factor of nutritive salt export, meanwhile, fertilizing amount and the interval between fertilization and rainfall-runoff events could affect nutritive salt exportation.