Aims: The Snail family member snail encodes zinc finger–containing transcriptional factor and is involved in heart formation.Yet,little has been known how Snail modulates the heart development.The aim of this study was to reveal the molecular mechanism of Snail involved in the heart development in embryos.Methods and Results: We determined the snail function during heart development in zebrafish embryos.One of the duplicated snail genes,snai1b,was identified in the heart field in zebrafish embryos.Snai1b knockdown induced cardiac morphological and functional defects,due to the defective migration of cardiac precursors.The layer of Fibronectin in the heart field was disrupted.The expression of α5β1 integrin was dramatically reduced.Injection of protein of α5β1 integrin rescued the layer of Fibronectin in extracellular matrix and restored the migration of cardiac precursors in the Snai1b knockdown embryos.Conclusion: Snail modulates the fabrication of Fibronectin for migration of cardiac precursors via controlling the expression of α5β1 integrin during heart development in zebrafish embryos.