Let G be a simple graph,Q(G)=D(G)+A(G) be the signless Laplacian matrix of G,and φ(G,λ)=??? be the characteristic polynomial of its signless Laplacian matrix.Giving p_n(G) of the characteristic polynomial of signless Laplacian matrix of bicyclic graph,it is proved that p_n(G) is determined by the base of G.