The invention discloses a preparing method of high-adhesive-force P(VDF-HFP) slurry. The preparing method includes the steps that a dispersing agent is added into deionized water and stirred and dissolved, a dispersing agent solution is prepared, an adhesive monomer and an inhibitor are added into the dispersing agent solution, the mixture is mixed and dissolved, then P(VDF-HFP) powder is added, stirring is carried out, and a mixed system is obtained; inert gas or nitrogen is introduced into the mixed system to eliminate air in the mixed system, and then sealing preservation is carried out; the mixed system which is subjected to sealing preservation in the step b is put into a <60> Co gamma-ray irradiation device and irradiated, and dispersion liquid is obtained; the dispersion liquid is centrifuged and washed to be anew dispersed into deionized water, and the P(VDF-HFP) slurry is prepared. The slurry prepared with the method has high adhesivity, and is used for coating of lithium ionbattery diaphragms, performance reduction and hidden danger which are caused by adhesive force losing are avoided, and the electrical performance and the safety performance of a lithium ion battery are fundamentally improved.