Ocean wave spectra are broad-banded, while wave energy conversion systems are designed to harvest energy efficiently within a narrow frequency range, resulting in low overall power capture efficiency. This paper aims to introduce a nonlinear vibro-impact power take-off (PTO) mechanism for a heaving point absorber, in order to broaden its power capture bandwidth and provide end-stop function. A mathematical model of the vibro-impact mechanism is derived, and numerical simulations are conducted under regular wave conditions, to investigate the effect of the vibro-impact mechanism on the system performance. Numerical results illustrate that the heaving point absorber with the vibro-impact PTO system exhibits a characteristics of band-pass effect, and the nonlinear vibro-impact mechanism has the potential to broaden power capture bandwidth, achieve end-stop function, and attenuate peak-to-average power ratio.