The invention discloses a nucleic acid for quickly detecting an A1166C polymorphic site of an AGTR1 gene and establishes a detection kit and a quick detection method for efficiently and sensitively detecting the A1166C polymorphic site of the AGTR1 gene. The detection kit has the characteristics of convenience in use, simple and convenient operation, high degree of automation, capability of greatly simplifying the operation process and reducing the pollution in the operation process, good detection effect, high sensitivity, high specificity, high accuracy and high precision. According to the detection method provided by the invention, the fully closed tube operation is adopted, the operation is simple, convenient and quick, the detection result is acquired in the manner of directly detecting a fluorescence signal value in a PCR process, the PCR post-treatment or electrophoresis detection is not required, the easiness in pollution and false positive of the conventional PCR technology can be overcome, the non-specificity amplification problem can be effectively avoided and the method is suitable for the detection of large-batch samples.