In this paper,a full discrete two-level scheme for the unsteady Navier-Stokes equations based on a time dependent projection approach is proposed. In the sense of the new projection and its related space splitting,non-linearity is treated only on the coarse level subspace at each time step by solving exactly the standard Galerkin equation while a linear equation has to be solved on the fine level subspace to get the final approximation at this time step.Thus,it is a two-level based correction scheme for the standard Galerkin approximation.Stability and error estimate for this scheme are investigated in the paper.