The invention discloses a bacillus having an ethanethiol degradation ability and an application thereof in environmental modification. According to the invention, a strain of bacillus having excellent degradation ability to the ethanethiol is screened out by separating and purifying activated sludge in a river in Guangzhou, and the bacillus is named as Bacillussp. GIGAN3, which is conserved in China Center for Type Culture Collection (CCTC C) on September 8, 2013; the address of the collection center is Wuhan University, Wuhan, China; the conservation number of the bacillus is CCTCC NO: M2013396. The bacillus GIGAN3 provided by the invention has good degradation effect on the ethanethiol in the environment, and can be applied to degrading the ethanethiol in the environment; therefore, the purpose of realizing environmental remediation is achieved.