Abstract: Aiming at the reservoir conditions of high temperature and high salinity in Lunnan 2TI oil group, the xanthan enhanced foam system was prepared by Lunnan 2TI formation brine, betaine surfactant and xanthan. This paper analysed the effect of foaming agent concentration, foam stabilizer concentration, temperature, salinity, volume fraction of oil and shearing times on foam performance by using high temperature and high pressure visualization foam meter, and the micromorphology of xanthan enhanced foam was characterized by microscope. The results showed that the foam volume and drainage half-life of xanthan enhanced foam were 365 mL and 58 min under the conditions of 2 000 mg/L foaming agent concentration, 2 000 mg/L xanthan concentration, 120 ℃, 200 572 mg/L salinity and 10 MPa. With xanthan concentration increased, foam volume decreased, half-life and liquid film thickness increased, the foam became uniformed and bubble size decreased, the change rate of bubble diameter and bubble number became slow, and xanthan optimum concentration was 2 000 mg/L. High temperature, high salt and oil would have negative effects on foam performance, but xanthan enhanced foam could be applied to the strict reservoir conditions with the temperature of 110-130 ℃, the salinity of 180 000-240 000 mg/L and oil volume fraction less than 10%. The foam volume increased and half-life decreased with the increasing of shearing time. After four times of high-speed shearing, the foam volume increment rate and half-life retention rate of xanthan enhanced foam were 13.6% and 77.6% respectively, the corresponding xanthan concentration was 2 000 mg/L, and it had strong repeating foaming ability and shear-resistant capacity.