The invention discloses ultra-high-count pure cotton combing yarn and a spinning technology of the ultra-high-count pure cotton combing yarn. Raw cotton comprises, by weight, 15%-25% of Egypt cotton, 25%-35% of American cotton and 40%-50% of Xinjiang long stapled cotton, wherein the Egypt cotton, the American cotton and the Xinjiang long stapled cotton are blended to spin 200S to 300S pure cotton yarn. The spinning technology includes the following steps that the first procedure of blowing-carding, the second procedure of combing, the third procedure of drawing, the fourth procedure of roving yarn, the fifth procedure of spun yarn and the sixth procedure of spooling. With the blending scheme, the raw cotton can integrate the advantages of high fineness and good maturity of the Egypt cotton, the advantages of high strength and non-existing abnormal fibers of the American cotton, the advantage of large length of the Xinjiang long stapled cotton and the like. The raw cotton reaches the requirements for the fiber length, the length CV value, the Micronaire value, the fineness, the strength and other performance indexes of raw cotton in producing ultra-high-count yarn. According to the spinning technology of the ultra-high-count pure cotton combing yarn, the ultra-high-count yarn can be produced under a large ration of roving yarn, the spinning efficiency is improved and meanwhile, quality of resultant yarn is ensured.