  The Kn\"odel graph $W_{\Delta,n}$ is a $\Delta$-regular bipartition graph on
$n\ge 2^{\Delta}$ vertices and $n$ is an even integer. The vertices of
$W_{\Delta,n}$ are the pairs $(i,j)$ with $i=1,2$ and $0\le j\le n/2-1$. For
every $j$, $0\le j\le n/2-1$, there is an edge between vertex $(1, j)$ and
every vertex $(2,(j+2^k-1) \mod (n/2))$, for $k=0,1,\cdots,\Delta-1$. In this
paper we obtain some formulas for evaluating the distance of vertices of the
Kn\"odel graph and by them, we provide the formula
$diam(W_{\Delta,n})=1+\lceil\frac{n-2}{2^{\Delta}-2}\rceil$ for the diameter of
$W_{\Delta,n}$, where $n\ge (2\Delta-5)(2^{\Delta}-2)+4$.
