Abstract: Helicoverpa armigera under the selection pressure of Bacillus thuringiensis toxin has developed resistance to Bt toxin in the field population. In order to study the Bt resistance in the field population of H. armigera, a series of resistance monitoring techniques were developed. This article introduces the principles, applications, advantages, and disadvantages of the bioassay methods and the molecular detection methods commonly used for monitoring Bt resistance of H. armigera. At present, the bioassay methods such as the F₁ screen and the F₂ screen are mostly used to monitor the Bt resistance in the field population of H. armigera, but the molecular detection methods with their advantages are playing an increasingly important role in the detection of Bt resistance of H. armigera. This review is expected to provide references and suggestions for readers to choose a suitable method of monitoring Bt resistance of H. armigera.