We experimentally simulate a parity-time (PT)-symmetric quantum dynamics in a non- Hermitian system using a single-photon interferometer. We measure quantum final state using quantum state tomography. We observe the quantum state evolutions ranging from regions of unbroken to broken PT-symmetry using the single-photon interferometer. We experimentally prove that the eigenvalue of energy changes from real to imaginary corresponding to the non-Hermitian system from the PT-symmetry unbroken region to the PT-symmetry broken region. To the best of our knowledge, this is the first work to intuitively show the exceptional points of PT-symmetry non-unitary quantum dynamics in a single-photon interferometer from the energy perspective.