The invention relates to a balanced type single-metal seal test apparatus. The balanced type single-metal seal test apparatus is mainly applied to test research of a single-metal seal in deep-well petroleum and natural gas exploitation and comprises a driving impact system, a circulating system, a pressure balance system, a sealing system, a loading system and a signal acquisition system. The designed single-metal seal experiment apparatus can perform a stand experiment on performance of the single-metal seal, comprehensively tests work performance of the single-metal seal, predicts sealing life, and has great significance in further studying and improving the performance of the single-metal seal; through a flexible oil bag and a balance cylinder, a dynamic balance between hydraulic pressure and lubricating oil pressure is realized, and the pressure transmission is more sensitive; underground working condition environment with impact vibration can be simulated, impact loading is performed in an experiment process, and an experiment result is enabled to be closer to real working environment of the single-metal seal during well drilling; and a lubricating oil cavity and a water cavity integrally moves on a guide rail such that an axial load is applied to the single-metal seal, and the displacement loading precision is improved.