The invention discloses a detection kit of ochratoxin and a method thereof for detecting the ochratoxin, and belongs to the technical field of detection of harmful substances. The detection kit of ochratoxin disclosed by the invention comprises a nucleic acid aptamer of the ochratoxin, a cDNA which is not completely complementary to the nucleic acid aptamer, and two hairpin sequences H1 and H2, wherein the sequence of the nucleic acid aptamer of the ochratoxin is as shown in a sequence table SEQ ID NO. 1; the two hairpin sequences H1 and H2 can be self-assembled into a long chain; and the cDNAwhich is not completely complementary to the nucleic acid aptamer of the ochratoxin can trigger the self-assembly of the hairpin sequences H1 and H2. The kit provided by the invention has very high sensitivity and specificity, simple operation and rapid detection, the result is visible to naked eyes, the kit is suitable for promotion in all laboratories, and real-time onsite analysis of the ochratoxin can be realized without professional training.