In this paper,the multiplicity of homoclinic solutions for second order non-autonomous Hamiltonian systems ü(t)-L(t)u(t)+▽uW(t,u(t))=0 is obtained via a new Symmetric Mountain Pass Lemma established by Kajikiya,where L ∈ C(R,RN×N)is symmetric but non-periodic,W ∈C1(R×RN,R)is locally even in u and only satisfies some growth conditions near u=0,which improves some previous results.