Abstract: A new type of optical voltage sensor based on the linear measurement of electro-optic phase retardation by using the crystal wedge is proposed.Which consists in having electro-optic hase retardation of crystal converted into the shift of light spot stripe,and phase retardation is acquired by measuring the shift of stripe.The linear relation between stripe shift and phase retardation is analyzed and derived,and the calculation method for shift of light spot stripe is provided.It is shown by experiment that the range of phase retardation measured,as an indication of linearity quality,has reached 320°.