The invention discloses a microgroove group composite phase change radiator. The radiator comprises a radiating surface and a condensing surface which are opposite to each other, wherein the radiating surface is connected with the condensing surface by a side surrounding plate to form a closed inner cavity, and a plurality of conveying pipelines for connecting the radiating surface with the condensing surface are arranged in the inner cavity; a microgroove group structure consisting of a plurality of microgrooves on micro level is arranged on the radiating surface in the inner cavity and used for accommodating a heat removal medium; a porous core material is filled in gaps between the conveying pipelines in the inner cavity; and a plurality of gaps are formed at one end of each conveying pipeline, which is in contact with the condensing surface, and the liquefied heat removal medium capable of being accommodated on the condensing surface flows out of the conveying pipelines and enters the porous core material. The radiator has heat superconducting capacity, and the heat of a power electronic equipment chip can be timely transferred to the radiating fin part by the microgroove group composite phase change technology; and the radiator is strong in cooling capacity, does not have cooling energy consumption, runs without power, saves energy, and is light in overall weight, small in size, stable in work, high in reliability, low in cost and environment-friendly.