Thioflavin T(ThT) can bind to G-quadruplex through non-covalent interaction to form G-quadruplex/ThT complex， showing strong fluorescence intensity， while free ThT fluorescence is very weak. In the presence of florfenicol (FF)， the high affinity of the aptamer(Apt) with a G-quadruplex structure to the target enables the formation of the Apt/FF complex and the release of ThT， resulting in a decrease in fluorescence intensity. Based on this feature， this study designed a sensitive and rapid on-site detection system for the detection of florfenicol， a label-free fluorescent aptasensor based on G-quadruplex/thioflavin T. The detection range of this aptamer sensor was 0.0128-200 ng/mL， the actual detection limit was 0.0128 ng/mL， and the total detection time was 10 min. At the same time， the recovery rate of the actual spiked samples (milk and eggs) was calculated， and the spiked recovery rate was between 91.2% and 117.1%. The established label-free fluorescent aptasensor has the advantages of high specificity， low cost， and short time-consuming， and can be used for on-site detection of actual samples.