Vibrio　parahaemolyticus　(V.　parahaemolyticus),　which　may　cause　gastrointestinal　disorders　in　humans,　is　a　pathogen　commonly　found　in　seafood.　There　are　many　methods　for　detecting　V.　parahaemolyticus,　yet　they　have　some　shortcomings,　such　as　high　cost,　labor-intensiveness,　and　complicated　operation,　which　are　impractical　for　resource-limited　settings.　Herein,　we　present　a　sequence-specific,　label-free,　and　colorimetric　method　for　visual　detection　of　V.　parahaemolyticus.　This　method　utilizes　CRISPR/Cas12a　to　specifically　recognize　the　loop-mediated　isothermal　amplification　(LAMP)　products　for　further　trans-cleaving　the　Gquadruplex　DNAzyme　and　depriving　its　peroxidase-mimicking　activity.　In　this　way,　the　results　can　be　directly　observed　with　the　naked　eyes　via　the　color　development　of　2,2＇-azino-di-(3-ethylbenzthiazoline-6-sulfonic　acid)　(ABTS(2-)),　which　displays　colorless　for　positive　samples　while　green　for　target-free　samples.　We　term　such　Cas12a-crRNA　preventing　ABTS(2-)　from　developing　color　by　trimming　the　G-quadruplex　DNAzyme　as　Cascade.　The　proposed　method　can　detect　9.8　CFU　(per　reaction)　of　pure　cultured　V.　parahaemolyticus,　and　the　sensitivity　is　comparable　to　real-time　LAMP.　It　has　been　applied　for　practical　use　and　showed　the　capability　to　detect　6.1　x　10(2)　CFU/mL　V.　parahaemolyticus　in　shrimp　samples.　Based　on　this,　the　newly　established　Cascade　method　can　be　employed　as　a　universal　biosensing　strategy　for　pathogenic　bacterial　testing　in　the　field.