The invention relates to the technical field of cooling assembly assembling, in particular to a device and method for automatically assembling a heat pipe radiator assembly. The device comprises a jig, a rack, a feeding conveying belt and an assembling conveying belt; the feeding conveying belt and the assembling conveying belt are located at the front end and the rear end of the rack correspondingly; and a buffering station provided with a jig in-place sensor, a heat transfer connection piece station, a cooling fin station, a glue coating station, a heat pipe station and an upper cover station are sequentially arrayed on the assembling conveying belt from front to back, wherein the heat transfer connection piece station, the cooling fin station, the glue coating station, the heat pipe station and the upper cover station are each provided with a positioning gear pin, an elastic positioning taper pin and a jig in-place sensor. The corresponding method includes the following steps of customization of the jig, feeding, assembling and combining, wherein the assembling step includes heat transfer connection piece placement, cooling fin placement, glue coating, heat pipe placement and covering and closing. The method that corresponding parts are positioned, placed and spliced step by step is adopted, automation and process operation of continuous assembling are achieved, the production efficiency is greatly improved, the assembling precision and the product quality are improved, and the labor intensity of workers is reduced.