A thermal interface material (10) includes 100 parts by weight of a silicone oil (11) and 800˜1200 parts by weight of a metal powder (12) mixed into the silicone oil. An outer surface of each metal particle (121) of the metal powder is coated with a metal oxide layer (122). A method of producing the thermal interface material includes steps of: (1) applying a layer of organo coupling agent on the metal powder; (2) heating the metal powder at a temperature between 200 to 300° C. to coat a metal oxide layer on an outer surface of the metal powder; and (3) adding the metal powder with the coated metal oxide layer to a silicone oil. The thermal interface material has an excellent thermal conductivity and an excellent electrical insulating property.