In view of the problem that the non-circular gear tooth profiles are complex and the measurement is difficult

so an elliptic gear is used as the study object.By using over roller measurement method

the technology of measurement such as section curve of error

the tooth thickness error

radial runout and tooth alignment error precision indexes and so on are studied.By establishing the mathematical model of an elliptical gear over roller measurement

the measuring principle of different elliptic gear modulus

the error evaluation basis

the types specification of measuring roller

and the matching relations are studied.A new method of precision measurement for various errors

which are section curve error

tooth thickness

tooth ring radial runout and tooth alignment error of non-circular gear is provided.