emerges as a promising candidate due to its great theoretical potential (energy density of nearly 2.3 MJ per cubic meter of water). [2] This osmotic energy can be obtained by employing ion-selective dense membranes, which is named as reverse electrodialysis. [3] Currently, the energy generation of reverse electrodialysis is primarily constrained by conventional ion-exchanged membranes (IEMs), [4] such as Nafion and microphase-separated membranes, owing to the limited ion flux efficiency and compromised selectivity. [5] With the attractive attention in nanofluidic that explores the ion and fluid transports at the nano-/subnano-scales, the primary considerations for designing high performance membrane-based SEG are high ion selectivity and permeability, which are also contradictory principles to construct efficient osmotic energy harvesting system. [6] Recently, a range of novel material have been studied to improve the performance of osmotic energy harvesting, such as 2D nanofluidic channels composed of graphene oxide (GO), [7] Mxene, [8] MoS 2 , [9] boron nitride, [10] and black phosphorus, [11] which have shown excellent ion transport along the in-plane direction, but exhibit poor performance in the transmembrane direction. Moreover, 2D layered membranes generally suffer from swelling [12] and even disintegration in water. [13] Another active research area in recent year is to prepare membranes with single nanopore, such as single MoS 2 nanopore, [14] which has raised the energy density into a new level of 10 6 W m −2 . However, it remains a challenge to fabricate such membranes on a macro-scale.Metal-organic frameworks (MOFs) with well-defined nanopores have emerged as an excellent nanofluidic platform for the osmotic energy generator. [2b,15] The 3D nanopores with functional groups provide a possibility to make a breakthrough in achieving both high ion selectivity and permeability for osmotic energy harvesting, which is due to the enhanced electrostatic interaction between the ions and MOFs with functional groups. [16] Moreover, the 3D nanochannels of MOFs offer massive ion transport pathways for high permeability. However, processing MOFs membranes with well-controlled functional groups and less-defects structure on a substrate plays the most important role on obtaining high performance osmotic energy generation. Even though an extensive control over the MOFs Ion-selective membranes are considered as the promising candidates for osmotic energy harvesting. However, the fabrication of highly perm-selective membrane is the major challenge. Metal-organic frameworks (MOFs) with well-defined nanochannels along functional charged groups show great importance to tackle this problem. Here, a series of dense sodium polystyrene sulfonate (PSS) incorporated MOFs composite membranes (PSS@MOFs) on a porous anodic aluminum oxide (AAO) membrane via in situ anodic electrodeposition process are developed. Benefiting to the novel structural design of the confined Ag layer, PSS@MOFs dense composite membrane with less defec...