The molecular dynamics simulations were conducted to investigate the effects of random roughness on nano-cutting of γ-TiAl alloys. To simulate the actual workpiece surface, the random surface roughness was generated by a multivariate Weierstrass-Mandelbrot (W-M) function under the condition of different rake angles of cutter and depths of cutting. The equivalent height of the workpiece was used to quantify the depth of cutting. The molecular dynamics simulation results reveal that the roughness has a profound effect on the nano-cutting quality of the workpiece. Besides, the effects of roughness are also different under different cutting parameters.