α-synuclein, a presynaptic protein, was found to be the major component of the lewy bodies in inherited and sporadic Parkinson’s disease（PD）. α-synuclein point mutations or genetic alteration can cause Parkinson’s disease（PD）. It is thought to be involved in the processes of neurodegeneration. This paper reviewed the toxic mechanisms of α- synuclein in Parkinson disease and α- synuclein transgenic animal models.