The differential equations of motion of a classical particle in the field of noncentral force are expressed in Ermakov formalism, and the Ermakov invariant is obtained. By rescaling the time, the parametric orbit equations of the classical particle can be expressed in terms of energy H and Ermakov invariant. The Noether symmetry, Lie symmetry and the form invariance of the transformations of two conserved quantities are studied in this paper. The result indicates that the transformations of the two conserved quantities not only possess Noether symmetry but also possess Lie symmetry and form invariance.