Recently, symplectic totally isotropic subspace inclusion graph [Formula: see text] on a [Formula: see text]-dimensional symplectic space [Formula: see text] was introduced in [J. He, S. Zhang and G. Zhang, Symplectic totally isotropic subspace inclusion graph, Linear Multilinear Algebra (2022), doi:10.1080/03081087.2022.2112016], which is a graph whose vertices are all totally isotropic subspaces of [Formula: see text] and two distinct vertices are adjacent if and only if one is contained in the other. In that paper, the authors studied the diameter, girth, clique number and chromatic number of [Formula: see text] and also studied some other properties of [Formula: see text]. In this paper, we determine the automorphism group of [Formula: see text].