Abstract: The objective of this study was to obtain the optimal basal salt medium of quinclorac degradation bacteria strain Z2 in the laboratory, which provided a theoretical basis for bacteria multiplying of Z2. Through enriching separating and screening from wastewater sludge around pesticide plant, we got quinclorac degradation bacteria strain. The bacterium, designated as Z2, was identified as Alcaligenes sp. In the single-factor test and orthogonal test, we measured the A_OD600 of Z2 and finally determined the optimal basal salt medium of degradation bacteria strain Z2. The results showed that optimal carbon and nitrogen sources were sodium citrate and yeast, and the optimal basal salt medium were sodium citrate 0.2%, yeast 0.7%, NaCl 2%, CaCl₂ 0.006%, FeCl₃ 0.0003%, K₂HPO₄ 0.05%, KH₂PO₄ 0.07%. Z2 could multiply in the optimal basal salt medium, which laid the foundation for its use in bio-remediation of contaminated soil.