摘要
By using the data of geomagnetic models and day-l ength variations, the paper calculates and analyzes the correlations from 1840 to 2010 between secular variations of geomagnetic parameters and decadal variations of day length. The calculated results show that the decadal variations of day length ahead of the lsecular variations of geomagnetic parameters by 8-11 years, moreover, decadal variations of day length and long-tem variations of geomagnetic parameters are probably homologous.