A micron iron-based primary battery material, preparation method and membrane bioreactor system are provided. The raw materials of the primary battery material include micron zero-valent iron particles and micron activated carbon particles, and the primary battery material is spherical particles with a BET specific surface area of 32-110 m.sup.2/g and a particle size of 15-25 mm; the method includes the following steps: loading micron zero-valent iron particles on the surface of micron activated carbon particles by using the bonding effect of a bonding agent, stirring, granulating and drying to obtain the product.