In the present article, the characteristics and the composition of the vibration-measuring system are introduced. The vibration-measuring system is composed of passive servo vibration pickup. This article focuses on the analysis of the nature of feedback and the principle on which the passive servo vibration pickup works. We also compared the characteristic difference of the system before and after feedback. some test data and examples of application are given. Anti-jamming problem of vibration-measuring system is analyzed. In addition, some conclusions are given.