Cyhalofop-butyl (CyB) is a widely used aryloxyphenoxy propanoate (AOPP) herbicide for control of grasses in rice fields. Five CyB-degrading strains were isolated from rice field soil and identified as Agromycessp., Stenotrophomonassp., Aquamicrobiumsp., Microbacteriumsp., and Pseudomonas azotoformans; the results revealed high biodiversity of CyB-degrading bacteria in rice soil. One strain, P. azotoformansQDZ-1, degraded 84.5% of 100 mg L–1CyB in 5 days of incubation in a flask and utilized CyB as carbon source for growth. Strain QDZ-1 could also degrade a wide range of other AOPP herbicides. An esterase gene, chbH, which hydrolyzes CyB to cyhalofop acid (CyA), was cloned from strain QDZ-1 and functionally expressed. A chbH-disrupted mutant dchbH was constructed by insertion mutation. Mutant dchbH could not degrade and utilize CyB, suggesting that chbHwas the only esterase gene responsible for CyB degradation in strain QDZ-1. ChbH hydrolyzed all AOPP herbicides tested as well as permethrin. The catalytic efficiency of ChbH toward different AOPP herbicides followed the order quizalofop-P-ethyl ≈ fenoxaprop-P-ethyl > CyB ≈ fluazifop-P-butyl > diclofop-methyl ≈ haloxyfop-P-methyl; the results indicated that the chain length of the alcohol moiety strongly affected the biodegradability of the AOPP herbicides, whereas the substitutions in the aromatic ring had only a slight influence.