In this paper, we investigate the orbital stability of solitary waves for the following generalized long-short wave resonance equations of Hamiltonian form: 0.1{iut+uxx=αuv+γ|u|2u+δ|u|4u,vt+β|u|x2=0.\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ \\textstyle\\begin{cases} iu_{t}+u_{{xx}}=\\alpha uv+\\gamma \\vert u \\vert ^{2}u+\\delta \\vert u \\vert ^{4}u, \\\\ v_{t}+\\beta \\vert u \\vert ^{2}_{x}=0. \\end{cases} $$\\end{document} We first obtain explicit exact solitary waves for Eqs. (0.1). Second, by applying the extended version of the classical orbital stability theory presented by Grillakis et al., the approach proposed by Bona et al., and spectral analysis, we obtain general results to judge orbital stability of solitary waves. We finally discuss the explicit expression of det (d^{prime prime }) in three cases and provide specific orbital stability results for solitary waves. Especially, we can get the results obtained by Guo and Chen with parameters alpha =1, beta =-1, and delta =0. Moreover, we can obtain the orbital stability of solitary waves for the classical long-short wave equation with gamma =delta =0 and the orbital instability results for the nonlinear Schrödinger equation with beta =0.