The present invention provides a method and a system for improving the precision of element measurement based on laser-induced breakdown spectroscopy. The method comprises: press-forming a sample to be measured with a tablet press; making a cavity on or immediately above a surface of the press formed sample; forming a layer of aerosol immediately above the surface of the sample to be measured with the components thereof completely identical to those of the sample to be measured; testing the sample to be measured by using a laser-induced breakdown spectroscopic system, so as to obtain the intensities of the characteristic spectral lines of a target element in the sample to be measured; and determining the concentration of the target element in the sample to be measured according to a calibration curve of the target element in prearranged calibration samples.