In　this　paper　we　propose　a　method　of　characteristic　value　extraction　for　image　reconstruction　by　using　step　light　probe　biological　tissue.　First　of　all,　the　method　shows　that　we　can　recover　the　spatial　distribution　of　the　optical　parameters.　What　is　more,　this　theory　can　be　applied　to　solve　the　problems　that　are　similar　with　optical　imaging.　No　matter　what　form　of　incentives,　we　can　calculate　their　response　using　the　forward　model,　and　find　the　physical　means　to　measure　the　response.　We　can　use　this　theory　to　solve　it.　This　article　is　a　verification　of　the　application　of　optical　imaging　to　the　problems　above.