Aiming at ultra-high water cut and high temperature reservoir in IV layers of Shuanghe oilfiled，a study carried out in situ microemulsion flooding with anionic-nonionic and anionic carboxylate compound surfactant B-1 and alkyl sulfonate surfactant A3-2. The oil displacement effect was compared between situ microemulsion flooding and surfactant/polymer binary compound flooding. The distribution characteristics of remaining oil，the microscopic oil displacement efficiency and mechanism of oil displacement in the process of situ microemulsion flooding were also studied by using high temperature and high pressure micro visual simulating technique. The results showed that 3% A3-2 or 3% B-1 solution had ultra low interfacial tension（10^-4 mN/m magnitude）and the property of situ forming microemulsion with crude oil，which had the solubilization parameter up to 20. A3-2 solution could form the middle phase microemulsion with crude oil in situ，and B-1 solution could form the lower phase microemulsion with crude oil in situ. The oil displacement efficiency of situ microemulsion flooding was better than that of surfactant/polymer compound flooding. A3-2 solution had better solubilization capacity and microscopic oil displacement effect than B-1 solution. The situ microemulsion flooding relied mainly on the solubilization between the surfactant and crude oil and formed microemulsion in the porous media，as a result，achieved the effect of miscible flooding. The flooding system could further improve oil recovery with the mechanism of carrying through emulsification，reducing the oil-water interfacial tension，improving core wettability and so on when the crude oil in micellar microemulsion solubilization reached saturation. In this process，clusters and porphyritic of residual oil were firstly removed，and ultimately the various types of remaining oil were effectively removed.