All-polymer　solar　cells　(all-PSCs)　based　on　amorphous　polymer　acceptors　show　different　phase　separation　behaviors　from　those　with　conventional　semicrystalline　polymer　acceptors.　In　this　work,　to　match　an　amorphous　polymer　acceptor,　we　have　designed　three　polymer　donors　with　the　same　conjugated　backbone　poly(benzo[1,2-b:4,5b＇]dithiophene　(BDT)-co-4,7-dithiophene-5,6-didecyloxylbenzo[2,1,3]thiadiazole)　but　with　zero,　two,　or　four　fluorine　substitutes　on　the　side　chains.　The　increasing　number　of　fluorine　substituents　leads　to　downshifted　LUMO/HOMO　energy　levels　and　more　serious　aggregation　behavior　of　the　polymer　donors.　The　polymer　bearing　four　fluorine　substitutes　(PD-4F)　matches　well　with　the　amorphous　polymer　acceptor.　Benefiting　from　the　optimal　phase　separation　morphology,　improved　charge　transport,　and　suppressed　charge　recombination,　the　PD-4F-based　all-PSC　device　shows　the　highest　device　performance　with　a　power　conversion　efficiency　of　6.45%.　These　results　indicate　an　effective　approach　of　side　chain　fluorination　to　design　polymer　donors　to　match　amorphous　polymer　acceptors　for　efficient　all-PSCs.