The utility model discloses a detecting system to different frequency carrier signal communication performance, it includes coupling module, frequency detection and selects module, bandwidth -limited circuit, select switch ZK, a plurality of relay and frequency spectrograph, goes out high frequency carrier signal through the coupling of coupling module, plays the effect that 50 hz power frequencies are kept apart, reduces decay low -frequency noise and interfering signal, provides as far as possible little decay and linear amplitude -frequency, frequency -phase characteristic to high frequency carrier signal, at first detecting the carrier signal frequency and showing through frequency detection and selection circuit, copy control and data processing unit drive select switch ZK and the corresponding relay bandwidth -limited circuit that selects to correspond the frequency draws high frequency signal simultaneously, final output to the frequency spectrograph performance analysis that communicates, can be in time effectively the analysis with judge the low pressure collection and copy the carrier communication problem of appearance in field commissionning or the maintenance.