We will give a new proof of the existence of hypercylinder expander of the inverse mean curvature flow which is a radially symmetric homothetic soliton of the inverse mean curvature flow in
$\mathbb {R}^{n}\times \mathbb {R}$,
$n\ge 2$, of the form
$(r,y(r))$ or
$(r(y),y)$, where
$r=|x|$,
$x\in \mathbb {R}^{n}$, is the radially symmetric coordinate and
$y\in \mathbb {R}$. More precisely, for any
$\lambda>\frac {1}{n-1}$ and
$\mu>0$, we will give a new proof of the existence of a unique even solution
$r(y)$ of the equation
$\frac {r^{\prime \prime }(y)}{1+r^{\prime }(y)^{2}}=\frac {n-1}{r(y)}-\frac {1+r^{\prime }(y)^{2}}{\lambda (r(y)-yr^{\prime }(y))}$ in
$\mathbb {R}$ which satisfies
$r(0)=\mu $,
$r^{\prime }(0)=0$ and
$r(y)>yr^{\prime }(y)>0$ for any
$y\in \mathbb {R}$. We will prove that
$\lim _{y\to \infty }r(y)=\infty $ and
$a_{1}:=\lim _{y\to \infty }r^{\prime }(y)$ exists with
$0\le a_{1}<\infty $. We will also give a new proof of the existence of a constant
$y_{1}>0$ such that
$r^{\prime \prime }(y_{1})=0$,
$r^{\prime \prime }(y)>0$ for any
$0<y<y_{1}$, and
$r^{\prime \prime }(y)<0$ for any
$y>y_{1}$.