The effects on the growth of fish (Gold cracian carp) and vegetables (Lactuca sativa L.) and the water quality of the system were studied by controlling iron content in feed. One control group and five treatment groups were set up in the experiment, with iron content of 0, 0, 10, 20, 40 and 80 mg/kg respectively. The results showed that the system has obvious effect on purifying the water. There was no significant influence of iron content on the survival rate of gold cracian carp (P>0.05), but there was significant influence on the weight gain rate (P<0.05). When iron content in feed was 20 mg/kg, the survival rate and weight gain rate of gold cracian carp both reached the maximum. When iron content in feed was 80 mg/kg, the survival rate and weight gain rate of gold cracian carp both decreased. There was no significant influence of iron content in feed on the survival rate and weight gain rate of the two vegetables (P>0.05), but there were some differences in weight gain rate. The results showed that addition of iron into feed could promote the growth of gold cracian carp and vegetables, and when the iron content was 20 mg/kg, the aquaponic system showed the optimal productivity.