In order to reveal the influence of two-dimensional nanosheet material（2-D smart black nano-card）on the stability of crude oil emulsion，taking the crude oil of Changchunling and Third Block of Fuyu oilfield as an example，the effect of 2-D smart black nano-card fluid with a mass fraction of 0.005% on the stability of crude oil emulsion was studied under the condition of 7∶3 water-oil volume ratio. The stability and interfacial film strength of crude oil emulsion were analyzed using stability analyzer and interfacial rheological instrument. The mechanism of smart black nano-card on enhancing the stability of emulsion was analyzed by observing the microscopic shape and particle size distribution of emulsion. The results showed that the size of smart black nano-card was about 70 nm × 100 nm and the thickness was 0.65—1.2 nm. The Pickering emulsion was formed by adding smart black nano-card to the emulsion composed of crude oil and 0.01% stabilizer cetyl trimethylammonium bromide（CTAB）. The ultimate dewatering rates of the emulsions slowed down，which decreased from 75.71%—78.57% to 65.71%—72.86% . The stability of emulsion increased and the turbiscan stability index（TSI）value decreased from 4.73—5.64 to 2.71—3.84. The strength of the emulsion film increased and the rheological characteristic of the system changed from viscosity to apparent elasticity. The backscattering spectra of the Pickering emulsions with smart black nano-card could be divided into three regions，such as emulsion demulsification zone， transition zone and emulsion coalescence zone. Smart black nano-card could change the hydrophilic-lipophilic balance of stabilizer，transform W/O emulsion into O/W emulsion and form emulsion with droplet size of 0.1—5 μm，resulting in greatly viscosity reduction of crude oil. Smart black nano-card had hydrophilic-lipophilic amphiphilic property，which could arrange on the liquid film through self-adsorption，increase the strength of liquid film and improve the stability of emulsion.