Abstract: XuJiahe Formation of Xinchang gasfield belongs to the low permeability, dense sandstone reservoir. The fracturing and acidizing of such complicated heterogonous formations is a baffling problem to the industry for years. Aiming at solving the problem, this paper introduces a new technology be known as equilibrium and closed fracturing acidizing and also presented its principles and designs. Field application at Xinchang 855 gas well indicates that this technology will effectively prolong rock-acid reaction time and form an acid corrosion fissure. Thus the well begins to produce gas after the flow back. This paper will have direct impact on the application of the new acid fracturing technology in China.