Abstract: According to the characteristics of the permanent magnetic field for room temperature magnetic refrigerator, a set of calculation formula are derived from using magnetic Coulomb's law.Based on the formula, the magnetic flux density of permanent magnetic paths for various room temperature of magnetic refrigerators can be calculated.The magnetic flux density calculated by the formula is fairly consistent with the one measured by experiment.The permanent magnetic field over (1.8 T) is designed by using the magnetic focusing technique.Several permanent magnetic fields are designed for the reciprocating and rotating magnetic refrigerators at room temperature.