Aim to investigate the effect of fluid shear stress on tissue factor (TF) high expression in endothelial cells and discuss its possible mechanism. Methods mRNA expression of TF, transcription factors nuclear factor Sp1 and Egr-1 and their relative antigen were analyzed by in sito hybridization and immunohistochemistry staining, respectviely. Functional TF activity was assessed by one-step recalcification clotting time assay, meanwhile, a simple parallel flow chamber system, which can produce 0～4.8 Pa steady laminar flow shear stress, was established in order to study the effect of blood flow shear stress on endothelial cells (EC). Results In hUVEC, TF functional activity, antigen and mRNA are very low; Sp1 protein expression increased in karyon, but the transcriptional activity of Sp1 is high in cytoplasm; Egr-1 mRNA and protein expresion is absent or fewer in karyon and cytoplasm. After 6 h exposed to 1.2, 2.4, 4.8 Pa shear stress, mRNA, protein expresion, the procoagulant activity of TF markedly increased comparing with control group (p<0.05). The mRNA and protein expresion of Egr-1 and Sp1 increased (p<0.05). However, the change of Egr-1 was more significant than that of Sp1 (p<0.05). The change trend of Egr-1 and Sp1 expresion were similar to that of TF. Conclusion The shear is one of a starting regulator of TF expression in endothelium. Their effect is mediated by transcription factors nuclear factor Egr-1 and Sp1.