  The harmonic index of a graph $G$, is defined as the sum of weights
$\frac{2}{d(u)+d(v)}$ of all edges $uv$ of $G$, where $d(u)$ is the degree of
the vertex $u$ in $G$. In this paper we find the minimum harmonic index of
bicyclic graph of order $n$ and diameter $d$. We also characterized all
bicyclic graphs reaching the minimum bound.
