  Recent experiments have reported a lot of spectacular transport properties in
topological materials, such as quantum oscillations and three-dimensional (3D)
quantum Hall effect (QHE) in ZrTe$_5$. In this paper, by using a strong
topological insulator model to describe ZrTe$_5$, we study the magnetotransport
property of the 3D system. With fixed carrier density, we find that there
exists a deferring effect in the chemical potential, which favors
distinguishing the saddle points of the inverted LLs. On the other hand, with
fixed chemical potential, the features of 3D QHE are demonstrated and we
attribute the underlying mechanisms to the interplay between Dirac fermions,
magnetic field and impurity scatterings.
