The invention discloses an automatic orientation method for a dipole magnetic roller. The dipole magnetic roller comprises a magnetic roller and a magnet used for attracting the magnetic roller; the magnetic roller comprises an aluminum pipe and a magnetic core installed in the aluminum pipe, a D-shaped shaft is arranged at one end of the magnetic core, and the end of the D-shaped shaft is assembled in a D-shaped hole formed in a rubber part; and the dipole magnetic roller is characterized in that one half of the magnetic core is magnetized into an N magnetic pole, and the other half of the magnetic core is magnetized into an S magnetic pole. The automatic orientation method comprises the steps that firstly, in the magnetic core magnetizing process, it is guaranteed that a fixed angle is formed between the boundary plane of the N magnetic pole and the S magnetic pole and a shaft marking face on the D-shaped shaft, and the D-shaped hole is provided with a hole marking face; and secondly, through attraction of a magnetic body to the magnetic roller, the magnetic roller rotates, the boundary plane of the magnetic roller and the horizontal plane keep a first fixed angle, and then the shaft marking face and the horizontal plane keep a second fixed angle.