Abstract: In this study, the bio-desilication experiment of fly ash using Bacillus amyloliquefaciens ZGW-12 is determined the optimal conditions for strain culture and bio-desilication of ore samples.The initial inoculation amount of bacteria culture is determined to be 5 mL, maintained at 125 r/min and the temperature of 30 ℃ for 4 days to reach a growth stable period.The best conditions for bio-desilication of fly ash are determined that 5 mL bacteria culture medium is inoculated in 100 mL sterilized medium with 7.5 g fly ash and it is bio-leaching at 30 ℃ and 150 r/min.The Si²⁺ concentration in the ore pulp with a particle size of less than 75 μm is all higher than 158 mg/L after 7 days bio-leaching, meaning the its bio-desilication is better.Bio-leaching the fly ash for 31 days measured that Si²⁺ concentration could reach 306 mg/L, while Al³⁺ concentration is basically maintained at 0.5 mg/L, illustrating that ZGW-12 have a good effect on the bio-desilication of fly ash.Combined with SEM-EDS and FTIR analysis, ZGW-12 is easily adsorbed on the surface of the fly ash, and the Si—O bond is broken in the ore sample, which had a good effect on extracting silicon and retaining aluminum with fly ash.