中文摘要：

利用BJ模型和国际地磁参考场（IGRF）模型资料，研究了地球主磁场的周期特点．结果表明，地磁偶极子磁矩变化率、功率谱变化率以及非偶极子磁场各阶球谐系数的平均漂移速率均存在60a左右的周期,其它与二阶项有关的地磁参数中普遍具有30a周期，且西向漂移的加权平均项及其二阶项也存在30a周期变化．因此60a和30a周期是地磁长期变化的主要特征周期．

英文摘要：

Based on the data of the Bloxham ＆ Jackson Geomagnetic model （BJ for short） and the International Geomagnetic Reference Field （IGRF）, the features of the geomagnetic main field periodicity are discussed. The results indicate that there is a periodicity about 60 years for the change rates of geomagnetic parameters, including geomagnetic moment, the spatial power spectrum and the average drift rate of spherical harmonic coefficients with different orders of the non-dipole magnetic field. And a 30-year periodicity is commonly available for the geomagnetic parameters and the averagewestern drift rate considering the weight factors and the terms that related to n = 2. Consequently, it can be confirmed that 60-year and 30-year are the main characteristic periods of geomagnetic secular variation.