Malachite　green　(MG)　was　decolorized　by　laccase　(LacA)　of　white-rot　fungus　Cerrena　sp.　with　strong　decolorizing　ability.　Decolorization　conditions　were　optimized　with　response　surface　methodology.　A　highly　significant　quadratic　model　was　developed　to　investigate　MG　decolorization　with　LacA,　and　the　maximum　MG　decolorization　ratio　of　91.6%　was　predicted　under　the　conditions　of　2.8　U　mL(-1)　LacA,　109.9　mg　L-1　MG　and　decolorization　for　172.4　min.　Kinetic　studies　revealed　the　Km　and　kcat　values　of　LacA　toward　MG　were　781.9　mM　and　9.5　s(-1),　respectively.　UV-visible　spectra　confirmed　degradation　of　MG,　and　the　degradation　mechanism　was　explored　with　liquid　chromatography-mass　spectrometry　(LC-MS)　analysis.　Based　on　the　LC-MS　spectra　of　degradation　products,　LacA　catalyzed　MG　degradation　via　two　simultaneous　pathways.　In　addition,　the　phytotoxicity　of　MG,　in　terms　of　inhibition　on　seed　germination　and　seedling　root　elongation　of　Nicotiana　tabacum　and　Lactuca　sativa,　was　reduced　after　laccase　treatment.　These　results　suggest　that　laccase　of　Cerrena　was　effective　in　decolorizing　MG　and　promising　in　bioremediation　of　wastewater　in　food　and　aquaculture　industries.