Objectives To unscramble the relation between biological action and cytoskeleton’s abnormity in tumor fromthe phenomenon that when A549 cell respons to strain morphological changes are induced. Methods A549 cell waschosen and an unidirectional equiaxial strain loading device in vitro was set up to apply cyclic stretch to the substrate ofthe cells, with the computer image processing and mathematical statistics. Results The results of the experiment wereanalyzed and compared with the contrast. It’s demonstrated that: 1. During the stretch course, the cells have presentedmorphologic changes clearly. The ratio of the long axis and short axis had increased obviously going with the cells spreadarea increased; 2. Nucleus spread area increased, the modality alteration which was induced by substrate stretch wasnot patency; 3. Cyclic stretch made orientation of the A549 cells change to the vertical direction of the stretch. Cells werestretched longer and linked head to tail in the form of a line. Conclusion: 1.The respondence of cytoskeleton componentsof A549 (mainly include cytoskeleton of membrane, cytoplasm and nucleus) to stretch are separate and unsynchronized;2. The respondence of A549 to the stretch is normal.