Exponential metrics are popular Finsler metrics. Let F be an exponential (α, β)-metric of isotropic S-curvature on manifold M. In this paper, a Lie sub-algebra of projective vector fields of a Finsler metric F is introduced and denoted by SP(F). We classify SP(F) of isotropic S-curvature as a certain Lie sub-algebra of the Killing algebra K(M, α).
