Fumaric acid is an important building-block chemical. The production of fumaric acid by fermentation is possible. Loofah fiber is a natural, biodegradable, renewable polymer material with highly sophisticated and pore structure. This work investigated a new immobilization method using loofah fiber as carrier to produce fumaric acid in a stirred-tank reactor. Compared with other carriers, loofah fiber was proven to be efficiently and successfully used in the reactor. After the optimization process, 20 g addition of loofah fiber and 400 rpm agitation speed were chosen as the most suitable process conditions. 30.3 g/L fumaric acid in the broth as well as 19.16 g fumaric acid in the precipitation of solid was achieved, while the yield from glucose reached 0.211 g/g. Three batches of fermentation using the same loofah fiber carrier were conducted successfully, which meant it provided a new method to produce fumaric acid in a stirred-tank reactor.