Due to characteristics of high temperature, high pressure, dense lithology, strong heterogeneity and natural fractures in carbonate reservoir of Feixianguan formation and Changxing formation in Puguang gas field, the adoption of conventional acid operation may result in quick acid rock reaction and large amount of fluid leak off, therefore, it is difficult to achieve the performance of acid fracturing. Based on Puguang gas field reservoir characteristics, we establish a calculating model of multistage alternating injection acid fracturing acid etching fracture conductivity and an evaluation model for the degree of acid fingering, and we carry out the experimental study of multistage alternating injection closed acid fracturing technique influencing factors. After application this technology in Puguang 9 well, gas production before acid fracturing is 10. 32×104 m3 / d and now increased to 123. 86×104 m3 / d, stimulating effect is significant.