The　application　of　the　protein　design　method　based　on　the　HNP　model　and　the　relative　entropy　theory　is　discussed　for　four　structural　classes　of　real　proteins,　and　the　results　are　compared　with　that　of　the　HP　model.　Testing　on　190　proteins　shows　that　this　method　is　generally　effective　for　the　different　structural　classes　of　proteins.　Further　studies　show　that　the　success　rate　of　this　method　on　regular　secondary　structures　is　higher　than　that　on　the　random　coil.　Additionally,　the　success　rate　for　different　types　of　amino　acids　is　also　analyzed.　It　is　found　that　the　success　rate　on　the　hydrophilic　residues　is　higher　than　those　of　the　other　two　types.　Furthermore,　the　success　rate　of　this　method　on　the　conserved　residues　is　higher　than　the　non-conserved　residues.　The　reasons　resulting　in　the　difference　of　the　success　rate　on　different　systems　were　also　analyzed.　All　analyses　mentioned　above　make　the　foundation　for　the　development　and　the　application　of　this　method　in　the　future.