Abstract: The well repairing by drawing casing and changingis a new technology for restoring a well of casing failure and is veryeffective. During the well repairing, the diameter of themilled sleeve is large and the clearance is small, so that thesticking of the milled sleeve becomes very serious. It often increases therepairing period and repairing cost. In this paper, thetheoretical model of preventing milled sleeve from sticking is establishedby a mechanical analysis. It takes account of bothpressure difference and sticking effect on the milled sleeve. On the basisof the model, the longest time for the milled sleeve stopped in the well iscalculated, so that it can be prevented from sticking. The main factorsof sticking milled sleeve are analyzed.