To prevent or reduce the formation of burr efficiently in metal cutting, it is necessary to reveal the burr formation mechanism. A finite element model of cutting-direction burr formation in orthogonal machining was presented in this paper. The simulation of the burr formation process was conducted. Undeformed chip thickness, rake angle, rounded cutting edge radius and workpiece material were included in cutting conditions, whose influences on burr formation were investigated, according to the simulation results. By comparing the results of the simulation and the experiment, good consistency is achieved which proves that the finite element model of burr formation in this paper is significant and effective to predict burr formation.