When　the　light　passes　through　a　scattering　mediumthe　wavefront　of　the　beam　is　disturbed　due　to　the　multiple　scattering　phenomena.　If　the　light　is　coherentscattered　light　from　different　optical　paths　will　interfereresulting　in　random　speckleswhich　causes　extreme　degradation　in　imaging　quality.　Using　wavefront　shaping　techniques　to　focus　light　through　strongly　scattering　media　is　significant　for　optical　microscopic　active　imaging　through　biological　tissues.　Howeverthe　feedback-based　optimized　wavefront　shaping　often　ignores　the　background　noise　light　when　focusingand　even　in　some　casesthe　light　intensity　of　a　background　bright　spot　can　even　exceed　1/3　of　the　target　point.　To　solve　this　problemthis　paper　proposes　a　different　iterative　method　from　the　previous　multi-objective　optimization　genetic　algorithm　aiming　to　suppress　the　background　noise.The　effect　of　the　population　scale　of　the　genetic　algorithm　and　the　number　of　modulation　units　of　the　spatial　light　modulator　on　the　focusing　intensity　and　convergence　speed　are　systematically　studied.　The　experimental　results　show　that　the　genetic　algorithm　can　converge　quickly　when　the　population　scale　and　the　number　of　modulation　units　reach　32　and　16　×　16respectively.　The　maximal　light　intensity　of　the　target　region　can　reach　250　or　more.　In　terms　of　convergence　speedthe　fastest　convergence　is　achieved　for　a　population　scale　of　48but　the　shortest　iteration　time　is　achieved　for　a　population　scale　of　32.　All　target　intensities　can　achieve　convergence　after　60　iterations　when　the　number　of　modulation　units　exceeds　16　×　16and　the　number　of　modulation　units　is　positively　correlated　with　the　iteration　time.　Considering　above　aspectsthe　best　focusing　performance　of　the　genetic　algorithm　is　achieved　when　the　population　scale　and　the　number　of　modulation　units　reach　32　and　16×16respectively.　After　determining　the　optimal　experimental　conditionsthe　study　of　suppressing　background　noise　is　conducted.　The　experiments　aim　to　enhance　the　signal-to-noise　ratio　and　propose　a　different　iterative　method　from　the　previous　multi-objective　optimization　genetic　algorithm.　The　feedback　function　is　changed　to　the　ratio　of　target　intensity　to　average　background　noise.　Henceiterative　calculation　aims　to　increase　target　intensity　and　suppress　background　noise　simultaneously.　The　results　show　that　the　optimized　algorithm　significantly　reduces　the　light　intensity　in　the　background　region　after　the　modulated　area　is　increased.　And　its　optimal　value　is　basically　equal　to　the　system　noise　of　the　cameraindicating　that　the　optimization　function　can　suppress　the　light　field　noise　in　the　modulated　background　region　to　the　lowest　level.　In　terms　of　suppressing　the　area　of　significant　noise　bright　spotthe　area　of　the　significant　noise　bright　spot　formed　with　the　optimized　algorithm　in　the　background　region　decreased　by　70.4%　compared　with　that　before　optimizationindicating　that　the　optimization　function　can　effectively　suppress　the　local　noise　bright　spot.　In　additionthe　quality　of　the　focused　spot　is　evaluated　by　extracting　the　contour　features　of　the　target　region.　After　obtaining　the　contour　featuresthe　circularities　of　the　initial　spot　and　the　optimized　spot　are　calculated　separately　using　the　circularity　formula.　The　circularity　of　the　initial　spot　is　0.83while　the　average　circularity　of　the　optimized　spot　is　0.9indicating　that　the　shape　of　the　optimized　focused　spot　is　closer　to　the　ideal　circular　spot.　Finallya　quantitative　correlation　model　between　the　background　average　light　intensity　and　the　modulated　area　is　proposed　based　on　the　experimental　results.　The　experimental　data　are　fitted　well　using　the　quantitative　modeland　the　fitting　results　yield　a　saturated　average　light　intensity　of　246.6　in　the　focused　regionwhich　is　consistent　with　the　measurement　results　of　previous　experiments.　It　shows　that　the　correlation　model　proposed　in　this　paper　can　not　only　describe　the　correlation　between　the　modulated　background　area　and　the　background　mean　light　intensity　wellbut　also　quantify　the　relationship　between　the　light　intensity　of　the　focused　area　and　the　modulated　background　area.　©　2023　Chinese　Optical　Society.　All　rights　reserved.