The invention relates to a macromolecular heat conducting composite material, in particular to a heat conducting adhesive and a preparation method and application thereof. The heat conducting adhesive is made of, by weight, 60-100 parts of softener, 20-60 parts of rubber flexibilizer, 50-150 parts of heat conducting filler, 2-10 parts of tackifier, 0.2-5 parts of antioxidant and 0.2-5 parts of antiager. The preparation method includes the steps: rolling the rubber flexibilizer, sequentially adding the softener, the heat conducting adhesive, the tackifier, the antioxidant and the antiager, and mixing for 1-2h at the temperature of 80-150 DEG C to obtain the heat conducting adhesive. The heat conducting adhesive has the advantages of freeness of curing, convenience in processing, excellent adhesion performance, high heat conductivity and the like. Close adhesion of devices can be realized only by application of a proper pressure at the normal temperature, and the heat conducting adhesive is cheap and environment friendly.