Membrane technology stands as a leading method for water and wastewater treatments. MXene, a type of two-dimensional material, has garnered significant interest as a promising next-generation membrane material. Its customizable pore structure, uniform pore size, and hydrophilicity make it highly suitable for membrane separation technologies. This manuscript elucidates the modification strategies employed and evaluates the performance of MXene-based membranes (MBMs). Initially, the preparation of MXene nanosheets, pivotal to membrane fabrication, is detailed. Subsequently, the fabrication methods of MBMs are presented, emphasizing filtration, coating assembly, and other fabrication techniques. Furthermore, we emphasize the modification strategies employed to enhance the performance of MBMs. These encompass the regulation of MXene nanosheets in terms of lateral size, terminal functional groups, and in-plane pores. Furthermore, adjustments are made to the membrane assembly processes, focusing on controlling interlayer spacing. This includes methods such as self-crosslinking, insertion, and the incorporation of hybrid functional layers. Additionally, surface modifications encompass the regulation of surface charge, surface wettability, and management of surface defects. Next, we delineate the key membrane applications, encompassing separation mechanisms and their promising utility. Lastly, we present the challenges and opportunities that MBMs face in the field of water purification, with the hope of providing profound insights into the design and synthesis of advanced MBMs.