Abstract: A fungus, M6, that displayed a powerful ability to degrade cellulose was isolated from the waste fermentation beds at pig farms using the CMC-Na plate and Congo red staining methods. ITS sequence of the isolated strain was blasted with those from NCBI database, and the phylogenetic tree constructed to arrive at a preliminary identification for the fungus as Penicillium oxalate. Subsequently, an optimized enzyme-producing fermentation process on a solid medium inoculated with the isolated fungi was established. It included the application of bran and CMC-Na as the carbon source, soybean meal as the nitrogen source, pH 6.0 at the start, 10% inoculation rate, and fermentation at 30℃ for 96 h. The carboxymethyl cellulase activity of the material increased 2.31 times due to the optimization that reached 1 446 U·g^-1. In a composting experiment on the fermentation beds inoculated with M6, EM or control, M6 and EM raised the bed temperature to greater than 50℃ on the 3^rd day after start of fermentation, and maintained at the level for 10 d and 6 d, respectively. The cellulose degradation rate was 41.1% with M6, 38.8% with EM, and 14.8% with control. It suggested that, among the 3 tested fungi, M6 was most efficient on the waste treatment for pig farms.