In-well packer and method for forming underground water circulating flow field based on in-well packer

The invention relates to an in-well packer and a method for forming an underground water circulating flow field based on the in-well packer. The in-well packer comprises a central pipe, a packing assembly, a driving assembly and a positioning ring, the packing assembly is arranged on the central pipe, and the cross sectional area of the packing assembly can be changed so as to change the contact state of the packing assembly and the well wall of the circulating well; the driving assembly comprises a power ring connected with one end of the steel framework; the positioning rings comprise the first positioning ring and the second positioning ring, and the positioning rings are connected with the center pipe and arranged on the two sides of the power ring in the mode that the deformation range of the steel framework can be limited by limiting the movement range of the power ring. The circulating method comprises the steps that the in-well packer is arranged between the water pumping pipe and the water injection