The embodiment of the invention provides a light spectrum continuous background removing device, system and method. The light spectrum continuous background removing device is applied to an LIBS (Laser-induced Breakdown Spectroscopy) system comprising a laser device, a spectrograph and an objective table; the light spectrum continuous background removing device comprises a polarizer; the polarizeris arranged between the objective table and an acquisition head of the spectrograph; a calibration sample set is placed on the objective table; the polarizer is used for separating light spectrums ofdifferent polarization states; the objective table, the polarizer and the acquisition head are collinear. The light spectrum continuous background removing device and system are ingeniously designedand an optimal rotation angle of the polarizer can be selected to filter and remove a continuous background in the light spectrum.