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Based on the analysis of liquid fertilizer deep application characteristics, against the problem of the artificial ditching and hard burying during the process of fertilizer deep application, a kind of device which can apply liquid fertilizer deeply was designed. Quadratic rotation orthogonal experiment was conducted to test the fertilization performance of this device, Design-Expert 6.0.1 software was used to analyze, then, the influence of interaction of pump pressure, nozzle diameter, the forward speed of soil-bin trolley and the closing valve opening to fertilization loss rate were obtained. Ultimately, the optimum performance parameters of liquid fertilizer device are ascertained: the pressure of liquid pump is 0.2MPa, the nozzle diameter of spraying-fertilizer needle is 3mm, the forward speed of soil-bin trolley is 0.975m/s, the opening of the closing valve is 60% and fertilization loss rate is 2.8%. With the optimum performance parameters of liquid fertilizer device, the verification experiment result shows that the obtained fertilizer amount from the optimum combination of parameters can meet the design requirement, and the fertilizer loss rate is the least.