The invention discloses a power quality signal detection device based on compressed sensing blind signal separation technology. The device comprises a signal conditioning module, which is used for adopting a voltage transformer or a current transformer to connect with a power grid, enabling a power quality signal in an electric system to be input and carrying out filtering through an anti-aliasing low-pass filter to obtain an interference high-frequency signal; a signal sampling module, which is used for carrying out multi-channel synchronous sampling conversion on m-path observation signals and enabling the signals to be input to a signal processing and analysis module in a digital input manner; and the signal processing and analysis module, which is used for carrying out Fourier transform when the digital signals are input to the signal processing and analysis module having an ARM management control function and a DSP calculation and analysis function to obtain complex matrixes, extracting spectrum amplitudes of the two paths of observation signals in the complex matrixes to form a spectrum scatter diagram, determining the number of source signals according to line direction, estimating a hybrid matrix through a clustering method, reconstructing each source signal through a CoSaMP algorithm, and storing the results and outputting and displaying the estimated value of the number of source signals, the estimated hybrid matrix and the separated source signals.