Abstract: Semiconductor heterostructure is one of the most important components of active optoelectronic devices. In this paper, the heterostructures of narrow-band gap Hg_0.7Cd_0.3Te semiconductor and wide-band gap CsPbBr₃ semiconductor quantum dot films were constructed. Through the study, it was found that Type-I heterostructures were formed by the quantum dots and Hg_0.7Cd_0.3Te film. Some electrons and holes in CsPbBr₃ perovskite quantum dot film were transferred to the valence band and conduction band of Hg_0.7Cd_0.3Te before radiation recombination, resulting in the decrease of fluorescence intensity of CsPbBr₃ perovskite quantum dot film. In addition, the photon radiation energy of perovskite was greater than the band gap of Hg_0.7Cd_0.3Te, and part of the fluorescence was absorbed by Hg_0.7Cd_0.3Te. Finally, the fluorescence intensity of CsPbBr₃ perovskite quantum dots film heterostructure decreased to 0.2 times that of CsPbBr₃ quantum dots film alone, indicating that Hg_0.7Cd_0.3Te film in Type-I heterostructures had an important modulation effect on fluorescence of CsPbBr₃ quantum dots film due to carrier transport at the interface.