Topological　physics　has　evolved　from　its　initial　focus　on　fermionic　systems　to　the　exploration　of　bosonic　systems,　particularly　phononic　excitations　in　crystalline　materials.　Two-dimensional　(2D)　topological　phonons　emerge　as　promising　candidates　for　future　technological　applications.　Currently,　experimental　verification　of　2D　topological　phonons　has　remained　exclusively　limited　to　graphene,　a　constraint　that　hinders　their　applications　in　phononic　devices.　Here,　we　report　experimental　evidence　of　topological　phonons　in　monolayer　hexagonal　boron　nitride　using　advanced　high-resolution　electron　energy　loss　spectroscopy.　Our　high-precision　measurements　explicitly　demonstrate　two　topological　nodal　rings　in　monolayer　hexagonal　boron　nitride,　protected　by　mirror　symmetry,　expanding　the　paradigm　of　2D　topological　phonons　beyond　graphene.　This　research　not　only　deepens　fundamental　understanding　of　2D　topological　phonons,　but　also　establishes　a　phononic　device　platform　based　on　wide-bandgap　insulators,　crucial　for　advancements　in　electronics　and　photonics　applications.