In this paper,we study isoparametric hypersurfaces in Finsler space forms by investigating focal points,tubes and parallel hypersurfaces of submanifolds.We prove that the focal submanifolds of isoparamet-ric hypersurfaces are anisotropic-minimal and obtain a general Cartan-type formula in a Finsler space form with vanishing reversible torsion,from which we give some classifications on the number of distinct principal curvatures or their multiplicities.