Abstract: In this paper,on the basis of the phase-space functional integral for a system with a singular higher-order lagrangian, the canonical Ward identities for such a system under the global transformation in extended phase space have been derived; the quantal conserved charge under the global symmetry transformation in extended phase space is obtained. In view of this conserved charge in general is different from Noether charge in classical theory.A preliminary application of this formulation to Yang-Mills theory with higher-order derivatives is presented;the generalized BRS Charge is deduced.It is shown that the advantage of this formulation is that one does not need to carry out the integration over canonical momenta in phase-space functional integral, which could not be done by usual practice.