摘要: Aim　Tostudy the Lie symmetries and the conserved quantities of holonomic systems with unilateralconstraints in phase space. Methods　The invariance of ordinarydifferential equations under the infinitesimal transformations was used to establish thedetermining equations and the restriction equations of the Lie symmetries of systems. Resultsand Conclusion　The structure equations and the form of conserved quantitieswere obtained, and the solution of the inverse problem was presented. Two examples weregiven to illustrate the application of the results.