Abstract: :In this paper,the structural parameters of sliding sleeves were optimized to ensure initiating pressure of internal sliding sleeve satisfy the requirements of field operations. In addition to strength enhancement of inner sliding sleeves,initiating pressures can be effectively increased in the proposed optimized design.Major factors that may affect the initiating pressure of internal sliding sleeve were identified by using the Plackett-Burman design method,then major influence factors were optimized based on the Taguchi method.The optimal combination of parameters was determined through variance analysis.Performance of the internal sliding sleeve before and after optimization were investigated through numerical simulation and experimental tests.The optimized parameters included angle of bracket width,18°;bracket length,170 mm;bracket thickness,5.5 mm;cone angle of bracket,89.5°,dip angle of jaw,115°and the cone angle of jaw,65°.The numerical simulation results showed that the initiating pressure of the internal sliding sleeve is enhanced from 4.8 MPa to 7.5 MPa.At the same time,the maximum stress of moving the internal sliding sleeve is increased from 992 MPa to 1 101 MPa,which is still below the allowable stress of the sleeve material.Experiment tests showed that the initiating pressures of an internal sliding sleeve is enhanced from 5.1 MPa to 7.9 MPa to meet field operation requirements.The results showed that the Taguchi method could be used as a reliable method in structural optimization of full bore stimulation sleeve of ball drop counting type.