Abstract: A lead sulfide detector has the advantages of high short-wave infrared sensitivity and low auger noise. The lead sulfide film synthesized by chemical bath deposition can be compatible with the CMOS semiconductor process, which is beneficial for identifying low-cost and high-performance surface array detectors. However, the current research on lead sulfide detectors synthesized by chemical bath deposition primarily focuses on the larger unit detectors. In this study, the synthesis of lead sulfide film was based on chemical bath deposition. Lead sulfide photodetectors of 10–200 μm size were prepared using an ion beam etching process and the photoelectric performance of the device was studied in terms of resistance, aspect ratio, line width, and other parameters. The results showed that the responsivity of the PbS photodetector increased gradually as the size decreased. Under the irradiation of 1550 nm short-wave infrared light, the responsivity of the 10 µm photodetector was 51.68 A/W, which was approximately 123 times the responsivity of the 200 μm photodetector. Moreover, the PbS photodetector also had a good wide-range photoelectric response at visible light and 2.7 μm infrared wavelengths. The micron-size detector of this study can provide support for the research of lead sulfide detectors.