By using the relationship between the adjoint equation and the linearized equation of the motion system, and by using the wellknown result that divergence expressions are characterized by annihilation under the full Euler operator, a multiplier method was adopted to construct the conserved quantities of the motion equations. The Lagrange function of the motion system is not necessary for this method. The FokkerPlanck equation was given to illustrate the application of this method, and its infinite conserved quantities can be obtained easily by using this method.