Stereology is an interdisciplinary method for 3D morphological study developed from mathematics and morphology. And it is widely used in medical image analysis and cell-biology studies. The laser scanning confocal microscopic images (LSCMI) of tumor cells are quantitatively analyzed by using stereological point counting method. Three groups of cells, B16F10, B16/Vector and B16/GPR4 cells suspended in culture media, are studied and 20 image sets of each are taken and used in the experiments. The results show that the control group B16/Vector has no significant differences as compared with the parental B16F10 cells, while the experimental group B16/GPR4 shows significant differences in the stereological parameters of the cellular surface area to volume ratio (Rsvc) and the relative cellular form factor (f) (p<0.05 for Rsvc, and p<0.02 for f, respectively), suggesting that B16/GPR4 cells have less surface protrusions and reduced irregularity. This is in line with the previous observations that GPR4 inhibits migration and invasion of tumor cell in the transwell assay. The combination of stereology and laser scanning confocal microscopic imaging techniques provides a quick and useful method in cell biology, and especially in cell morphology studies.