The　full　utilization　of　incident　light　is　vitally　important　for　boosting　the　photoelectrochemical　activity　of　photoelectrodes.　Herein,　we　introduce　Ni-BiVO4　nanoarrays　for　mediating　the　photoelectrochemical　water　splitting　by　optimizing　the　optical　modes.　Highly　ordered　Ni-BiVO4　nanoarrays　were　fabricated　using　a　nanoimprinted　AAO　templating　technique.　By　controlling　the　thickness　of　BiVO4,　we　efficiently　regulate　the　photoelectrochemical　activity,　and　the　photocurrent　was　up　to　0.91　mA　cm(-2)　at　1.4　V　versus　Ag/AgCl　under　100　mWcm(-2)　in　the　visible　light,　which　is　3.25　times　that　of　a　flat　Ni-BiVO4　electrode　with　the　same　deposition　cycles　of　BiVO4.　The　optimal　efficiency　of　a　Ni-BiVO4　nanoarrray-based　photoelectrode　can　be　attributed　to　the　optimal　morphology,　which　has　the　lowest　reflection,　the　strongest　scattering　and　the　induced　strongest　absorption　for　the　incident　light　among　the　nanoarrays　samples　with　different　thickness　of　BiVO4.　This　work　demonstrates　the　importance　of　the　optimization　of　optical　modes　in　the　nanoarray　photoelectrode　in　order　to　boost　photoelectrochemical　activity.