Ochratoxin A (OTA) is a common mycotoxin that often contaminates food and causes different degrees of harm. In this study， a novel fluorescent aptamer sensor based on hybridization chain reaction (HCR) was developed for the rapid and sensitive detection of OTA in food products. Firstly， OTA binds to the aptamer and releases the trigger strand cDNA， which then triggers the HCR reaction between the hairpin HP1 and HP2， resulting in the formation of a G-quadruplex structure of G-quadruplex sequence in HP1， and at the same time， the N-quadruplex structure of G-quadruplex sequence in HP1. Sequence to form a G-quadruplex structure， while at the same time N-methylmesoporphyrin IX (NMM) dye is inserted into the G-quadruplex structure (G-quadruplex)， which significantly enhances the fluorescence signal. The enzyme-free and fluorescence-free quantitative detection of OTA was achieved by the change of fluorescence signal intensity. The results showed that the method was highly specific， and among the seven groups of tests， the results of the two groups containing OTA were positive， and the results of the other five groups without OTA were negative. The linear regression equation was Y = 0.71133lgCOTA+3.21383 with the correlation coefficient R2=0.9942， the linear range was 0.1 pg/mL - 5 ng/mL， and the limit of detection was 0.1 pg/mL. The recoveries of this method applied to the detection of artificially spiked samples of wheat， red wine and coffee were all in the range of 92%-97.88%， which were higher than those of the recoveries of the ELISA kits (90.5%-95.78%) indicated that the method was superior to the national standard method. Therefore， the novel fluorescent aptasensor developed in this study can realize the rapid， sensitive， specific and accurate detection of OTA in food， and also provides a new idea for the rapid detection of other toxins as well as other chemical contaminants affecting food safety.