Antimony　sulfide　Sb2S3　is　an　emerging　photovoltaic　absorber,　which　has　been　widely　studied　on　synthesis　route,　device　structure　and　interface.　However,　its　device　performance　is　still　limited　by　the　unoptimized　Sb2S3　absorber　and　interface　recombination,　in　which　the　neglected　character　of　thickness　is　unclear.　Here,　the　effect　of　absorber　thickness　on　the　Sb2S3　thin　film　solar　cell　was　carefully　investigated　in　the　range　of　80-620　nm,　aiming　to　reveal　the　trade-off　between　charge　separation　and　light　absorption　in　the　device.　The　characterization　of　JV　and　Sb2S3　thin　film　found　that　too　thin　Sb2S3　would　lower　the　VOC　and　JSC,　which　was　attributed　to　the　severe　shunt　and　insufficient　absorption.　While　the　too　thick　Sb2S3　would　hinder　the　charge　separation.　This　tendency　was　also　confirmed　by　the　performance　simulation　of　device.　Finally,　the　best　power　conversion　efficiency　of　4.96%　is　achieved　with　a　544　nm　Sb2S3　absorber.　This　work　provides　the　guidance　to　optimize　the　thickness　of　Sb2S3　absorber　for　solar　cells.