The invention discloses a positioning method of a circle center projecting point of coplanar circles, which constructs a quadratic curve according to an ellipse of the coplanar double circles on a camera image plane to obtain the characteristic value and the characteristic vector of the quadratic curve so as to obtain the perspective projection invariant point of the coplanar double circles and the structural parameters of the double circles, and utilizes the principle that anharmonic ratio is unchanged to determine the real projecting point of the circle center of the double circles on the image plane. The positioning method can determine the real projecting point of the circle center of the double circles without knowing any structural parameters of the coplanar double circles and can obtain the structural parameters of the double circles, and the method is simple and feasible and has better practicability and reliability.