Abstract: Sand production of fine loose sandstone is one of increasingly serious questions during gas reservoirs product,but methods about controlling sand are not found. Cavity completion well methods are introduced for increasing production and controlling sand, and applicability, condition and methods of producing cavities are introduced in the paper. Stress of surrounding rocks is analyzed, and the formula about critical productivity is given. The effects of all type of parameters to critical productivity are studied, and the analysis is given combined three gas wells in Qinghai gas field. Cavity completion well is good method in increasing production and controlling sand, and it will become an effective method to control sand through research.