Abstract: Sand control strings are used in most oil and gas wells on the platforms of the Chengdao Offshore Oilfield, and gel systems suffer shear in the process of injection and underground flow. To solve this problem, the shear actions of sand-screening pipe and strata on the gel in the process of construction were simulated in the laboratory, and the viscosity retention rate, gelation time, gel strength and sand pack plugging effect of the gel system used for the profile control in the Chengdao Oilfield after being sheared by sand-screening pipe and sand pack were studied. It is experimentally indicated that after the shear of the optimized gel formula by the sand-screening pipe, the viscosity retention rate is higher than 80%, the gelation time is increased slightly, but the gel strength is not changed. After through the sand packs with different permeability, the viscosity retention rate of the gel is 88.1% and 94.3%, respectively, the gelation time of base fluid is prolonged slightly, but the gel strength is unchanged, and the plugging rate of the gel in the sand packs of different permeability is 95%, 98.9% and 99.7%, respectively. It is revealed that after being sheared by sand-screening pipe and strata, the optimized gel system can still satisfy the requirements of field construction.