Loaded string is constructed by bonding some masses on a homogeneous string. When the elastic wave travels on the string meet one of the masses，it will partly penetrate the mass and partly reflect back，this is similar to the action of a potential barrier or well on quantum probability wave. Based on this similarity，we demonstrate in this paper the avoided crossing of energy levels，energy band in periodic structure and localization of eigenstate in random structure by the dynamics of a loaded string. We hope this experiment that can help students to understand those intriguing quantum phenomena.