The invention provides a vibration monitoring system of a reactor and reactor internals, solving the problems of reliability, compatibility, stability and maintenance convenience and comprising an accelerometer, a charge amplifier, signal conditioning equipment, vibration signal analyzing equipment, a display terminal, vibration monitor software and the like. In the signal conditioning equipment,a signal conditioning module carries out programmable amplification and low-pass filter on vibration signals, and a multi-channel selection module receives control signals of a self-check control module of the vibration signal analyzing equipment so as to realize system programmable self check; the vibration signal analyzing equipment comprises a PXI bus crate; the vibration monitor software calculates vibration characteristic frequency and amplitude of each channel as well as a CPSD value, a coherence value and a phase value of each channel pair and monitors vibration acceleration and amplitude of a pressure vessel of the reactor, a first order modal frequency and amplitude and a second order modal frequency and amplitude of a reactor fuel assembly, frequency and amplitude of a core barrel beam mode and a second order shell mode as well as swinging frequency and amplitude of the pressure vessel, and the like.