Objective—Vascular endothelial growth factor A(VEGFA)regulates both vasculogensis/angiogenesis and heart development.We aimed to study precious functions of VEGFA signaling in vascular development.Approach and Result:—We use transcription activator-like effector nuclease(TALEN)and tol2 transposon to establish mutant and overexpression lines of vegfaa in zebrafish respectively.Vegfaa-/-mutants are embryonic lethality and vegfaa+/-can survive to adulthood.Vegfaa-/-shows defects in differentiation of dorsal aorta and posterior cardinal vein accompanying unregulated and delayed intersegmental vessel sprouting.The arterial cells are absolutely absent in vegfaa-/-while the venous cells were greatly expanded.Mesencephalic veins in midbrain are obviously defect in both mutants and ectopic over-expression embryos.Conclusion—Our Result demonstrate vegfa regulates vascular development by promoting arterial fate.Both brain and trunk developmental vessels are required for vegfa signaling.Midbrain vessels are more sensitive and regulated in a strict dose-dependent requirement.