The existing contact type inspection needs to be divided into voltage levels, using different inspection equipment, and the non-contact test can not identify the voltage level, and the voltage level directly determines the safe distance of live operation. Non contact identification of voltage level is important to non-contact inspection and early warning of electric equipment. Based on the measurement of distance and electric field, a method of non-contact identification of voltage level is studied by using the theory of polynomial regression analysis. By collecting the electric field and distance data of 10kV, 35kV and 110kV, the three fitting functions are obtained respectively, and the polynomial regression analysis is carried out to realize the discrimination of the voltage grade of the three kinds of voltage. At the same time, a voltage level non-contact identification device is developed to identify and validate the method. The experimental results show that the three voltage levels can be well recognized.