Abstract: Aiming at the problem of high iron concentration existing in the flowback fluid for acidizing the high temperature carbonate reservoir, simulation evaluation methods of iron on aciding effects are established, the influence relation of iron on the acidizing effects are discussed. After injecting acid with iron content of 1 500~5 000 mg/L, the core permeability reduced to 60%~67% of the initial permeability. According to the mechanism of multi-groups bridging iron becoming stable materials, acidizing fluid system of controlling iron precipitation was developed. Stable iron concentration in reacted acid(pH > 3) reduced to 4 650 mg/L from 5 000 mg/L at 150℃, the damage of reacted acid on core permeability was less than 20%.