In this paper, a scheme for frequency-entanglement preparation is proposed and demonstrated based on the coherent manipulation of the frequency nondegenerate energy-time entangled state through an unbalanced Mach–Zehnder interferometer (UMZI). The principle of the coherent manipulation process is analyzed theoretically and demonstrated by experiments of nonclassical two-photon interference under different phase differences between the two arms in the UMZI, showing a fringe visibility of (96.9±1.0)%. The frequency-entangled two-photon state can be prepared under a proper phase difference, which is demonstrated by an experiment of spatial quantum beating with a fitting visibility of (99.0±0.8)%. The proposed scheme provides a simple and general way to prepare frequency-entangled states from the frequency nondegenerate energy-time entangled state, which can be easily realized through setups based on fiber optics.