We analyze a formulation of QED based on the Wilson renormalization group. Although the ''effective lagrangian'' used at any given scale does not have simple gauge symmetry, we show that the resulting renormalized Green's function correctly satisfies Ward identities to all orders in perturbation theory. The loop expansion is obtained by solving iteratively the Polchinski renormalization group equation. We also give a new simple proof of perturbative renormalizability. The subtractions in the Feynman graphs and the corresponding counter-terms are generated in the process of fixing the physical conditions.