The invention discloses a microwave-assisted laser-induced breakdown spectrum device which comprises a laser device, a microwave generator, a pulse delay generator, a collimation system, a spectrograph and an optical focusing system, wherein the laser device is firstly triggered by the pulse delay generator to emit a pulse type laser beam; the laser beam is collimated by the collimation system, and then the energy of the laser beam is focused on the surface of a sample through the optical focusing system; the laser beam and the sample interact with each other so as to generate high-temperature high-density plasma; and then the microwave generator is triggered by the pulse delay generator to emit a microwave pulse and the microwave pulse is controlled to stimulate the plasma again; under the effect of electromagnetic field, the electrons in the plasma are accelerated, so that sufficient kinetic energy is acquired for stimulating atoms and ions again; the electrons under the atom and ion stimulating state transit to lower energy level; during transition, a spectral signal is emitted, namely, a characteristic spectrum with specific wavelength is emitted; the spectrograph is triggered by the pulse delay generator again to collect the spectral signal.