The invention provides an insulating and heat-conducting double-sided adhesive tape and a preparation method thereof. In the insulating and heat-conducting double-sided adhesive tape, the outer layers on both sides are release paper, and a single layer of insulating and heat-conducting adhesive is arranged between the two layers of release paper. Or the outer layers on both sides are release paper, a single-layer substrate is arranged between the two layers of release paper, and an insulating and heat-conducting adhesive is arranged between the substrate and the release paper. The preparation method is as follows: mixing heat-conducting medium and solvent, adding insulating heat-conducting glue, stirring, coating and drying, and the preparation is completed. The adhesive tape of the invention has the advantages of good thermal conductivity, electrical insulation, stability at room temperature, easy die-cutting, reworkable characteristics, and easy operation.