Abstract: Since there is no way to realize the rigidity connection between jacked pipe and internal steel pipe, keeping a synchro-deformation between jacked pipe and heated steel requires an efficient unti-shear strength between internal steel pipe and insulating material, insulating material and the surface of jacked pipe. The author has studied the testing method on unti-shear strength at connecting area between jack and foam through analyzing property of thermal deformation transforming occurred in insulated pipe which is produced by one step technical process with jack and foam also has tested unti-shear strength at connecting area between two kinds of jacks and foams formed by "one step process" and "pipe in pipe process" with self-designed testing sevices, indicating that the unti-shear strength of insulated pipe produced by "pipe in pipe process" is obvious advanced to those insulated pipes produced by "one step process".