Metalenses　have　attracted　a　great　deal　of　research　interests　due　to　the　property　of　light　controllability.　How　to　enhance　the　focusing　effect　of　metalens　has　always　been　a　key　problem　that　many　researchers　have　been　working　on.　In　this　paper,　we　propose　a　novel　sub-dimensional　resonance-based　optimization　method　for　dielectric　metalens　with　golden　angle　spiral　arrays.　The　waveguiding　effect　is　first　applied　to　the　initial　design　of　the　quasiperiodic　metalens　through　the　defined　equivalent　period.　Then　the　genetic　algorithm　is　improved　for　adjusting　the　sub-dimensional　structure　of　the　initial　metalens.　The　optimization　results　show　that　the　peak　intensity　of　central　hot　spot　increases　by　32　%　while　keeping　the　full　width　at　half　maximum　(FWHM)　almost　unchanged.　At　the　same　time,　the　field　intensity　of　side　lobes　around　the　hot　spot　decreases,　which　means　that　a　potential　way　for　high-contrast　imaging　is　provided.