  We investigate the 3D quantum Hall effect in Weyl semimetals and elucidate a
global picture of the edge states. The edge states hosting 3D quantum Hall
effect are combinations of Fermi arcs and chiral bulk Landau levels parallel to
the magnetic field. The Hall conductance, $\sigma_{xz}^H$, shows quantized
plateaus at Weyl nodes while tuning the magnetic field. However, the chiral
Landau levels manipulate the quantization of Weyl orbits, especially under a
tilted magnetic field, and the resulting edge states lead to distinctive Hall
transport phenomena. A tilted magnetic field contributes an intrinsic initial
value to $\sigma_{xz}^H$ and such initial value is determined by the tilting
angle $\theta$. Particularly, even if the perpendicular magnetic field is
fixed, $\sigma_{xz}^H$ will change its sign with an abrupt spatial shift of
edge states when $\theta$ exceeds a critical angle $\theta_c$ in an experiment.
Our work uncovers the unique edge-state nature of 3D quantum Hall effect in
Weyl semimetals.
