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For theoretical analysis effect of self-adjustment flow on the adaptive drip irrigation emitter, the original size and pre-deformation deflection after fixed of the elastic adjustment diaphragm on the control volume were designed, and the total force to the elastic adjustment diaphragm based on description of its structure and working mechanism were analyzed. The theory and calculation method of mechanics to calculate the stress, the stiffness, the effective area of diaphragm and the sealing pressure ratio at interface of rubber adjustment diaphragm and energy dissipation hole were used. Then the actual sealing pressure ratio of the together control force was obtained. Results indicated that the minimum of actual sealing pressure ratio was 0.61 MPa at the combined action of the force produced from the pre-deflection and soil negative pressure of 20 kPa, but the computational theoretical sealing pressure ratio was 0.61 MPa too. The former was equal to the latter in both of them and met the condition of the actual sealing pressure ratio which was equal to or greater than the theoretical sealing pressure ratio. So the minimum of actual sealing pressure ratio was enough to maintain the drip emitter at the mode of initial shutoff water, and in a critical state of shutoff water and supply water. As long as soil negative pressure was bigger slightly when soil was drought little by little and it was equal to 21 kPa only or more than it, the actual sealing pressure ratio reduced to 0.54 MPa and far less than the theoretical sealing pressure ratio. Then the adaptive drip irrigation emitter began to drip water, and entered the mode of automatic regulation. So it had realized the effective of self-adjustment drip flow really at the same time. 