Conjugated polymers (CPs) have recently gained increasing attention as photocatalysts for sunlight-driven hydrogen evolution. However, they suffer from insufficient electron output sites and poor solubility in organic solvents, severely limiting their photocatalytic performance and applicability. Herein, solution-processable all-acceptor (A -A )-type CPs based on sulfide-oxidized ladder-type heteroarene are synthesized. A -A -type CPs showed upsurging efficiency improvements by two to three orders of magnitude, compared to their donor-acceptor -type CP counterparts. Furthermore, by seawater splitting, PBDTTTSOS exhibited an apparent quantum yield of 18.9% to 14.8% at 500 to 550 nm. More importantly, PBDTTTSOS achieved an excellent hydrogen evolution rate of 35.7 mmol h  g and 150.7 mmol h  m in the thin-film state, which is among the highest efficiencies in thin film polymer photocatalysts to date. This work provides a novel strategy for designing polymer photocatalysts with high efficiency and broad applicability.