in this talk, using the local ricci flow, we prove the short-time existence of the ricci flow on noncompact manifolds, whose ricci curvature has global lower bound and sectional curvature has only local average integral bound. the short-time existence of the ricci flow on noncompact manifolds was studied by wan-xiong shi in 1990s, who required a point-wise bound of curvature tensors. as a corollary of our main theorem, we get the short-time existence part of shi's theorem in this more general context.