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MnBi₂Te₄ is considered as an intrinsic antiferromagnetic topological insulator. We have successfully synthesized MnBi₂Te₄ single crystals. The magnetic susceptibility measurements indicate that the Neel temperature T_N = 25 K with the easy axis along the c direction. Below T_N, the system undergoes a spin flop transition at H_sf when the magnetic field (H) is applied along the c axis with H > H_sf. The critical field H_sf increases with decreasing temperature, reaching 3.5 Tesla at 2 K. Correspondingly, both the magnetoresistance and Hall resistivity show anomaly at H_sf. Detailed data analysis and implication will be presented.