Abstract: Narrowband photodetectors play a pivotal role in high-tech applications such as optical communication, biomedical imaging, and industrial sensing. However, current detectors have yet to outperform conventional vacuum detectors in terms of detection range, response speed, and dark current, primarily due to the environmental sensitivity and stability limitations of perovskite materials. This paper presents the fabrication and characterization of a self-filtering narrowband perovskite photodetector. By optimizing the surface morphology and grain size of perovskite films and exploiting the bandgap tunability of these materials, we demonstrate self-filtering capabilities in three specific wavelength ranges: 476～494 nm, 526～544 nm, and 586～604 nm. This innovation enables precise narrowband spectral responses essential for applications requiring high spectral selectivity. Systematic testing confirms significant performance enhancements within the target wavelength bands. The device achieves a responsivity of 106 mA/W, a twofold improvement in response speed, and a dark current reduction from 10 nA to 5 nA. These advancements directly address the limitations of current perovskite-based detectors. Comparative analysis shows that the self-filtering detector outperforms existing perovskite and vacuum photodetectors in terms of detection precision, response speed, and noise characteristics. Its high performance and self-filtering capabilities make it a promising candidate for applications in optical communication, industrial process control, safety inspection, and medical imaging. The proposed device not only overcomes the current bottlenecks of perovskite-based detectors but also paves the way for further advancements in narrowband photodetection technologies. This work underscores the potential of perovskite materials to revolutionize the photodetector industry and highlights the importance of continued research in this field.