  Hinge states are the hallmark of the 3D higher-order topological
insulator(HOTI). Here, we show that chiral hinge states can be identified by
the magnetic field induced Aharonov-Bohm(AB) oscillation of the electron
conductance in the interferometer constructed by HOTI and normal metal. Unlike
AB interferometer of 3D topological insulator(TI), we find that there are
different AB oscillation frequencies for a given direction of magnetic field in
3D HOTI. And the oscillation frequencies are also strongly depending on the
direction of magnetic field. The main conclusion in our work is that there
exists a universal linear relation between different oscillation frequencies.
Here, by constructing an interference model of hinge states loops, we show both
analytically and numerically that the linear relation is fulfilled in the HOTI
effective model. The four basic frequencies in the work are labeled as
$\omega_x$, $\omega_y$, $\omega_{x+y}$, $\omega_{x-y}$ and the main linear
relations we demonstrate here are $\omega_{x\pm y}=\omega_x \pm \omega_y$.
These results provide an effective way for the identification of the chiral
hinge states, and the oscillation signatures are stable with different sample
size and bias.
