Three-dimensional topological nodal lines, the touching curves of two bands in momentum space, which give rise to drumhead surface states, provide an opportunity to explore a variety of exotic phenomena. However, solid evidence for a flat drumhead surface state remains elusive. In this paper, we report a realization of three-dimensional nodal line dispersions and drumhead surface states in phononic crystal. Profiting from its macroscopic nature, the phononic crystal permits a flexible and accurate fabrication for materials with ring-like nodal lines and drumhead surface states. Phononic nodal rings of the lowest two bands and, more importantly, topological drumhead surface states are unambiguously demonstrated. Our system provides an ideal platform to explore the intriguing properties of acoustic waves endowed with extraordinary dispersions.

三维拓扑结点线，动量空间中两个频段的接触曲线产生了鼓面的表面状态，为探索各种奇异现象提供了机会。但是，关于鼓面表面状态平坦的确凿证据仍然难以捉摸。在本文中，我们报告了声子晶体中三维节点线色散和鼓面表面状态的实现。得益于其宏观性质，声子晶体可以灵活，准确地制造具有环形节点线和鼓面表面状态的材料。明确显示了最低两个频段的声子节环，更重要的是，拓扑鼓面的表面状态。我们的系统提供了一个理想的平台，可探索具有非凡色散的声波的迷人特性。