For the radial high-temperature superconducting magnetic bearing used in centrifugal helium cold compressor, the magnetic field calculation and structural design method of permanent magnet rotor are given, and the calculation of radial force and radial stiffness is carried out. A superconducting bearing performance measurement platform was built, and bearing rotor space magnetic field and bearing performance were measured. The calculation and measurement results show that the magnetic field calculation method is feasible and the result is accurate. The maximum external magnetic field at 1 mm from the outer surface of the permanent magnet rotor is about 0.5 T. The calculated radial force under field cooling and zero field cooling conditions both increase with the increase of the rotor eccentricity, which is in good agreement with the measurement results in linearity and trend. The measured radial stiffness value of the measured bearing in this paper is 362.4 N/mm, which is close to the calculated radial stiffness 334.594 N/mm, under field cooling conditions. The radial force calculation method described in this paper can be used for the qualitative radial stiffness calculation and design of high-temperature superconducting magnetic bearings, which has certain guiding significance for the application research of superconducting bearings.