The　concept　of　shadow　price　often　appears　in　the　finance　and　economics　related　literatures.　The　economic　meanings　of　shadow　prices　relative　to　a　special　variable　in　different　model　can　be　quite　different.　This　paper　develops　an　optimal　bank　non-performing　loans　dynamic　model　and　examines　the　economic　meaning　of　the　shadow　price　in　the　model　-the　Hamiltonian　multiplier　of　bank　non-performing　loans　growth　rate.　The　shadow　price　is　obtained　by　a　negative　marginal　utility　value　related　to　the　non-performing　loans　multiplying　by　the　parameter　of　the　utility　function.　Furthermore,　the　shadow　price　can　be　treated　as　a　marginal　cost　of　the　bank　non-performing　loans.