  We derive the $\Sigma$-$D$ relation of Galactic supernova remnants of
shell-type separately at adiabatic-phase and at radiative-phase through two
sets of different formulas, considering the different physical processes of
shell-type remnants at both stages. Also statistics on Galactic shell-type
remnants about 57 was made. Then we do some comparison with other results
obtained before. It shows that all the best fit lines in the $\Sigma$-$D$
relation plots newly are to some extent flatter than those derived by some
authors at early time. Our theoretical and statistical outcomes are in somewhat
good consistency.
