The invention relates to a composition of black and white electrophoretic display liquid for electrophoretic display and a preparation method thereof; the black and white electrophoretic display liquid respectively adopts carbon black and titanium dioxide nanoparticles as black and white electrophoretic particles; the concentration of the particles in the black and white electrophoretic display liquid is respectively 3 percent to 20 percent and 10 percent to 50 percent, and the mass ratio of the black and white electrophoretic display liquid is 1:15 to 1:30; the dispersion media are Isopar series, the dispersing agents are fluorinated surfactant and polymer dispersant, and the used amount of the dispersing agents is 3 percent to 40 percent of the used amount of the electrophoretic particles. The preparation method of the black and white electrophoretic display liquid comprises the steps that: first, the black and white particles, the polymer dispersant and the dispersion media are respectively ball milled to prepare the black and white electrophoretic display liquid, are mixed by a certain ratio, and are added with the fluorinated surfactant, so that the black and white electrophoretic display liquid is prepared. The electrophoretic display liquid is prepared into a micro-cup device, the spacing of two polar plates is 0.1mm, 15V forward and backward alternating voltage is applied, the response of the electrophoretic display liquid is good, the contrast is above 23:1 and the highest contrast is 38:1, the black display response time is 831ms, and the white display response time is 1123ms.