objective: To explore the cause of the eggs shell of E.vermicularis presented deformation during the making of the sample of paraffin section. Methods:Based on the morphologic feature of eggs shell and the recived pressure which was presented during the sample of eggs was made, the internal stress of eggs was analysed by meaus of the theory of elasticity-plastic mechanic. Result and Conclusion: The permanent deformation of egg-shell in paraffin-section caused by an overpressue bring to bear on the egg-shell out during the sample was made using improper technigue. The most deformed place of egg-shell were located in the lateral.