From the perspective of pore structure type, gas cleaning membranes can be divided into particle stacking membranes and fiber constructed membranes. The particle stacking type mainly includes ceramic membranes and metal membranes, and the fiber constructed type mainly includes biaxially stretched nanofiber membranes, electrospun nanofiber membranes, etc. From the perspective of membrane structure, it can be divided into symmetric and asymmetric membranes. In this Chapter, the structural features of the membrane material such as microstructure, porosity, pore size distribution, and membrane thickness will firstly be systematically introduced. Then, the key performance indicators such as gas permeability, filtration performance, corrosion resistance, thermal shock resistance, and service life will be successively detailed.