  Theoretical models show that the power of relativistic jets of active
galactic nuclei depends on the spin and mass of the central supermassive black
holes, as well as the accretion. Here we report an analysis of archival
observations of a sample of blazars. We find a significant correlation between
jet kinetic power and the spin of supermassive black holes. At the same time,
we use multiple linear regression to analyze the relationship between jet
kinetic power and accretion, spin and black hole mass. We find that the spin of
supermassive black holes and accretion are the most important contribution to
the jet kinetic power. The contribution rates of both the spin of supermassive
black holes and accretion are more than 95\%. These results suggest that the
spin energy of supermassive black holes powers the relativistic jets. The jet
production efficiency of almost all Fermi blazars can be explained by
moderately thin magnetically arrested accretion disks around rapidly spinning
black holes.
