  As the advent of precision cosmology, the Hubble constant ($H_0$) inferred
from the Lambda Cold Dark Matter fit to the Cosmic Microwave Background data is
increasingly in tension with the measurements from the local distance ladder.
To approach its real value, we need more independent methods to measure, or to
make constraint of, the Hubble constant. In this paper, we apply a plain
method, which is merely based on the Friedman-Lema\^itre-Robertson-Walker
cosmology together with geometrical relations, to constrain the Hubble constant
by proper motions of radio components observed in AGN twin-jets. Under the
assumption that the ultimate ejection strengths in both sides of the twin-jet
concerned are intrinsically the same, we obtain a lower limit of the $H_{\rm
0,min}=51.5\pm2.3\,\rm km\,s^{-1}\,Mpc^{-1}$ from the measured maximum proper
motions of the radio components observed in the twin-jet of NGC 1052.
