Abstract: In view of problems of low water and fertilizer utilization rate and poor fertilizer uniformity in domestic agricultural production，a set of precision variable water and fertilizer integration equipment were developed.It regarded requirements for nitrogen，phosphorus，potassium and trace elements in growth stages of crops as a variable.PLC collected soil moisture and flow information，and controled opening of proportional solenoid valve.HMI as an operator interface，which could not only display soil moisture information and liquid fertilizer flow，but set fertilizer ratio and irrigation time.By field test，the device had advantages of accurate formula fertilization，simple operation and good stability.