A graph is half-arc-transitive if its automorphism group acts transitively on vertices and edges, but not on arcs. It is known that for a prime there is no tetravalent half-arc-transitive graphs of order or . Xu [M.Y. Xu, Half-transitive graphs of prime-cube order, J. Algebraic Combin. 1 (1992) 275–282] classified the tetravalent half-arc-transitive graphs of order . As a continuation, we classify in this paper the tetravalent half-arc-transitive graphs of order . It shows that there are exactly nonisomorphic connected tetravalent half-arc-transitive graphs of order for each odd prime .