  The Alon-Tarsi number of a graph $G$ is the smallest $k$ for which there is
an orientation $D$ of $G$ with max outdegree $k-1$ such that the number of
Eulerian subgraphs of $G$ with an even number of edges differs from the number
of Eulerian subgraphs with an odd number of edges. In this paper, we obtain the
Alon-Tarsi number of a Halin graph equals 4 when it is a wheel of even order
and 3 otherwise.
