This paper investigates the single-photon scattering properties in a chirally-coupled system of a three-level V-type giant atom with a pair of waveguides. The two transitions of the three-level V-type system are chirally coupled with the two waveguides separately, and the two excited states are coupled by a classical light field. Then, the single-photon scattering amplitude is obtained by the real-space Hamiltonian method. The results reveal that one can realize the nonreciprocal single-photon frequency convertor and beam splitter with the efficiency of 1 under ideal conditions by the manipulation of the classical light field. The single-photon scattering properties depend on the accumulated phase by the photon propagation between the two coupling points of the giant atom and the waveguides. By controlling the phase, one can realize a single-photon frequency convertor and beam splitter with high frequency sensitivity to the incident light.