In this study, a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method is developed for in -situ quantitative imaging of trace impurity elements in Bi4Si3O12 (BSO) crystals. This method has unique advantages of low detection limit and high spatial resolution for the analysis of defects in crystal microregions. The regression coefficients of the calibration curves for each element were greater than 0.99, and the detection limits (DLs) were 17, 5, 7, 48, 5, 7, 16, 27, and 7 ng/g for 24Mg, 45Sc, 48Ti, 90Zr, 139La, 146Nd, 172Yb and 208Pb, respectively. The LA-ICP-MS measurements were in good agreement with the results obtained using conventional ICP-MS method. Segregation phenomena of elemental impurities in the axial direction of the BSO crystal can exist during crystal growth. Finally, the distribution of the impurity elements in the dendritic crystal defect region of the crystal was visualized. We believe that this work proposes a novel less-invasive analysis method for exploring the composition-defect relationship of crystals.