Abstract: The experiment was conducted to determine the weed eco-economic threshold in no-tillage summer corn field. Field plots were random complete block design. Weed species and density were setup using additive method. Weed eco-economic threshold was calculated by the relationship between the weed density and yield loss rate. The results showed that, yield loss rate (y) correlated positively with weed density (x). The fitted curve models were optimized by goodness of fit >0.90 and minimal residual sum of squares. Exponential model (y=46.4359-18.518e-x/21.9215-28.5039e-x/126.5527, R2=0.9609) was the optimum equation to fit for the relationship. Average eco-economic threshold in the field was 2.27 plants per m2. Permitted minimum weed density of the no-tillage summer corn field could be calculated by the model and instructed the weed integrative management.