Objective To optimize the process of making cell blocks by residual pleural and peritoneal effusions, and to explore its value in pathological diagnosis. Methods Totally 150 residual pleural and peritoneal effusion specimens of thinprep cytologic test (TCT) were evenly divided into 3 groups according to cytopathological diagnosis. Specimens in the three groups were processed by direct centrifugal method, egg white as the bracket method and cell block test method. The detection rate of malignant cells, distribution status and morphological features of cells on the cellular sections were compared between the three different methods, and the immunohistochemical staining results were compared between the cell block and tissue block. Results The TCT yielded a detection rate of malignant cells of 31.3% (47/150), and examination of the cell block in this study yielded a detection rate of 40.7% (61/150), with the rates of direct centrifugal method, egg white as the bracket method and cell block test method being 26.0%(13/50), 46.0%(23/50) and 50.0%(25/50), respectively. The detection rates of malignant cells in egg white as the bracket method and cell block test method groups were significantly higher than that in the direct centrifugation method (P<0.05); in addition, the former two groups also had better cell aggregation and distribution. The immunohistochemical staining results of cell blocks were also similar to those of tissue blocks. Conclusion The cell blocks processed by egg white as the bracket method and cell block test method can improve the detection rate of malignant cells in residual pleural and peritoneal effusion, and the blocks can be used for immunocytochemistry staining.