Objective: To study the effects of static tensile strain on the cytoskeleton of human periodontal ligament fibroblasts (HPLFs). Methods: Tensile strain with the strain variate of 8%,12%,16% and 20% was applied in the culture of HPLFs for 1,2 and 3 d respectively with a self-devised loading apparatus. With the aid of laser scanning confocal microscope, the projected areas of each observed cell and its nuclear were calculated and the cell cytosketeton was observed. The data analysis was carried out with SPSS using Dunnett test. Results:The projected areas of the cells and nucleus incereased with the increace of loading time and tensile strain value in trial groups of 8%,12% and 16%(P