  A simple but effective method for regularization-renormalization (R-R) is
proposed for handling the Feynman diagram integral (FDI) at one loop level in
quantum electrodynamics (QED). The divergence is substituted by some constants
to be fixed via experiments. So no counter term, no bare parameter and no
arbitrary running mass scale is involved. Then the Lamb Shift in Hydrogen atom
can be calculated qualitatively and simply as $\Delta E(2S_{1/2})- \Delta
E(2P_{1/2})=996.7 MHz$ versus the experimental value $1057.85 MHz$.
