Abstract: The effect of hyperon isospin interaction on the moment of inertia of neutron stars is examined in the framework of relativistic mean field theory for the baryon octet n,p,Λ, Σ-, Σ0, Σ+,Ξ-,Ξ0system.It is found that,as the xρ separately chosing as 2,1,2/3,the moment of inertia of neutron stars,that corresponding to the same mass and that corresponding to the same radius if R13.961km all decrease.But for the moment of inertia of neutron star as R13.961km,corresponding to the same mass,it is smallest if xρΣ=2/3,larger if xρΣ=2 and largest if xρΣ=1.