Abstract: Aiming at the problem of no-clear relationship between the screen blocking sand holes and formation median grain size of sand control screen completion in Dagang oilfield,by adopting the combination of theoretical models and laboratory experiments,the relationship is derived.Through the analysis and comparison,the grit aperture is improved from0.88 D50 to 1.27D50,and horizontal well productivity index increased by 30%.The statistical analysis of production situation shows that proper amplification of grit aperture can meet the needs of the sand control,and to increase the production of horizontal well.