Abstract: The ternary CuInS₂ quantum dots were prepared using thioglycolic acid as modifiers by hydrothermal synthesis method. Based on the fact of the fluorescence intensity of CuInS₂ quantum dots could be quenched remarkably by neomycin, a method for determination of neomycin with ternary CuInS₂ quantum dots as fluorescent probe was established. The optimized conditions found were as follows:① amount of Tris-HCl buffer solution of pH 8.0:0.5 mL; ② concentration of CuInS₂ quantum dots:2.0×10^-7mol·L^-1; ③ time of reaction:5 min. Linear relationship between values of the fluorescence quenching intensity and concentration of neomycin was obtained in the range of 1.0×10^-8-2.0×10^-7mol·L^-1, with detection limit (3s/k) of 2.0×10^-10mol·L^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 98.4%-106%, with RSD's (n=5) in the range of 1.9%-2.4%.