Magnetic resonance imaging (MRI) magnets are usually shimmed after manufacture to improve the uniformity of the magnetic field within their imaging region. This paper describes a new passive shimming (PS) method and a novel shimming procedure to correct magnetic field inhomogeneities in Biplanar permanent MRI magnets. The method achieves a practical balance between the magnetic field, harmonics, and shim weight/configuration by adjusting the importance ratio of the overall field uniformity to specific harmonic components. In the implementation, all raw magnetic field data on the surface diameter of the spherical volume (DSV) are first collected using a field sensor or camera; then, the target field map is compared with the measured raw field map, and the shimming procedure is run to optimize the thickness and position of the shims; after the shims are placed on the magnetic poles, a new field map is obtained, and the shimming algorithm is rerun to perform PS adjustments on the new field. This process is repeated until the field uniformity and harmonics meet the requirements required for imaging. The proposed algorithm is tested on a 0.2 T MRI permanent magnet and the results show that compared with the traditional linear programming (LP) method, the new method improves the field uniformity by 51% in the test scenario while using less spacer material and maintaining similar computational cost.