Xinjiang Nine-Six reservoir is a shallow and high-heterogeneity heavy oil reservoir. In the later stage of steam flooding, there are some problems such as high water cut, low oil-steam ratio, serious overlap and channeling of steam, low sweep efficiency and low oil recovery. In order to further enhance the oil recovery, the profile control performance through the application of in-situ gel system in the late stage of steam flooding has been studied. Firstly, the gelling strength, microstructure and temperature-resistance behavior of the in-situ gel have been estimated by frequency-elastic modulus scanning, electron microscope scanning and thermogravimetry（TG-DTG） respectively. Then the 3D physical simulation experiment has been carried out to investigate the gel’s profile controlling performance. The experimental results show that after the addition of thickened cellulose in the original system, the gel’s elastic modulus increases from 96.5 Pa to 316 Pa, indicating the great increase of gel strength. The microstructure of the gel is tighter, the cross-linking is stronger and the stability has been enhanced. Weight retention rate of the gel is higher than 90 % as the temperature increases to 160 ℃, and the temperature-resistance has been improved. In the later stage of steam flooding, after injection of gel solution into high-permeability layer and its transformation into gel, the injection pressure and the oil/steam ratio increase remarkably while the water cut reduces dramatically. The sweep efficiency increases by 31.96 % and the oil recovery by 14.07 %. The in-situ gel can cement oil sand, and block the channeling path of high-permeability layer, which effectively suppresses the steam channeling and overlap. Subsequently, the injected steam can easily enter the low-permeability layer to displace crude oil, resulting in the drastically increasing of sweep efficiency and oil recovery, and indicating the remarkable profile control performance in deep parts.