A method for making a thermal interface material includes: providing a CNT array on a substrate; providing a first solution with organic matter and ferric ion; soaking the CNT array into the first solution for a period of time; dipping a second solution into the first solution to form a ferric salt deposit; taking out the CNT array, and then heating the CNT array in inert gas; and cooling and peeling off the CNT array from the substrate, and finally achieving a thermal interface material. The thermal interface material made by the present method has a high heat conducting efficiency.