Abstract: High-resolution continuum source atomic absorption spectrometer（HR-CS-AAS) without alternating hollow cathode lamp used for simultaneously quantitative determination of Ca and Mg with single sample introduction was reported in this paper. Results showed that comparing with certified values of the standard samples the relative determination deviations were less than 5% and the sample analysis efficiency was remarkably improved. Continuous radiation source provides flexibility in selection of elemental determination lines. The results from the determination of Mg in 30 soil samples showed that the accordant analytical results were obtained by using primary and secondary sensitive lines (285 nm and 202 nm respectively), but the correlation coefficient of the calibration curve from secondary sensitive line (202 nm) is better than that from primary sensitive line (285 nm) for the samples with high Mg content. Compared with linesource atomic absorption spectrometer, sensitivity of HRCS AAS was improved notably.