In　polymer　solar　cells　(PSCs)　which　are　typically　processed　from　solution,　the　molecules　inside　the　active　layer　accumulate　disorderly,　which　greatly　hinders　the　exciton　dissociation　and　carrier　transport,　especially　in　thick　active　layers.　Here,　we　propose　an　effective　and　simple　strategy　to　solve　such　problem　in　poly　[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3　＇＇＇-di　(2-octyldodecyl)　2,2＇;　5＇,2　＇＇;　5　＇＇,2　＇＇＇-quaterthiophen-5,5　＇＇＇-diyl)]　(PffBT4T-20D)　polymer　based　thick　active　layer　by　regulating　the　polymer　crystallize　behavior　via　incorporating　two　synergistic　additives　diphenylether　(DPE)　and　1-chloronaphthalene　(CN)　during　the　film　processing.　The　as-prepared　active　layer　enables　the　PSC　exhibiting　a　remarkable　high　photoelectric　conversion　efficiency　of　10.93%,　which　is　much　higher　than　the　standard　PSC　fabricated　without　additives　under　the　same　conditions　(9.05%)　or　with　single　additive.　The　high　PCE　of　the　PSCs　is　a　result　of　the　highly　ordered　molecular　packing　and　the　formation　of　three-dimensional　charge　transport　channels　of　the　polymer　donor.　It　is　evidenced　that　the　microstructure　of　the　active　layer　treated　simultaneously　with　DPE　and　CN　undergoes　a　double　change　in　the　orderly　stacking　of　the　alkyl　chain　and　the　pi-pi　bond,　which　is　more　favorable　for　the　charge　transport.　The　results　indicate　that　the　active　layer　with　two　synergistic　additives　can　be　used　as　an　effective　and　convenient　method　for　controlling　the　film　morphology　in　the　polymer　solar　cells.