Foam acid has the advantages of high viscosity，low filtration and easy backflow，but the poor performance of high temperature tolerance and high salt tolerance are seriously restricting the application of the foam acid system in Tahe oilfield. In order to improve the acidification effect of foam acid in horizontal well，a new type of deep penetration foam acid system with high temperature and salt resistance，composed of 20% HCl+1% iron stabilizer XC-16 +2% corrosion inhibitor XC-13 +1% demulsifier XC-08 +0.9% blowing agent FRC-1+0.3% stable foam agent CNC+1.5% inorganic SiO2 nanoparticles，was developed，then the stability，salt resistance and acid rock reaction of the foam system was investigated. Experiment results showed that the viscosity of the foam acid was more than 40 mPa·s after sheared for 30 min at the temperature of 150℃ and at the shear rate of 170 s ^-1，which indicated that the temperature resistant performance of the foam acid was better than that of the gelled acid，the viscosity under the same experimental conditions being of 20 mPa·s. The foam acid system developed in the study was able to maintain good foaming and foam stabilization performance in 10×10⁴ mg/L high salinity conditions，the foaming volume was 400 mL and the foam half-life was 2435 s. The systems were arranged in order of the acid rock reaction rate at the temperature of 150℃，the sequencing was foam acid