The KKY in Tarim oilfield, Western China, is a typical HTHP deep dolomite reservoir (150C, 110Mpa and 6000m). The formation was deeply damaged with the heavy mud, and the matrix acidizing can't effectively eliminate the skin. But the acid fracturing treatment can't be carried because the surface pressure exceeds the working pressure capability of conventional 15,000psi fracturing equipment. To effectively decrease the surface treating pressure, a new high density acid system was developed. Its density is adjustable within the range of 1.25-1.55 g/cm3. Extensive laboratory test was conducted to evaluate its corrosion inhibition capacity, stability, rheological properties etc. The performance of the acid system can totally qualify for the need of high temperature, and effectively lower the surface treating pressure about 25Mpa. The new weighted acid ensured the acid fracturing successfully in KKY reservoir, with the treating pressure up to 94Mpa. And the production increased considerably after the acid fracturing with the high density acid in several wells.