<p indent="0mm">The surface plasmon effect based on metal nanoparticles can enhance the local electric field strength and exhibit excellent light trapping capabilities, which can effectively improve the performance of optoelectronic devices. In this study, combined with the Finite Difference Time Domain (FDTD) method and magnetron sputtering technology, the effects of metallic Al nanoparticles on the photoelectric characteristics of β-Ga<sub>2</sub>O<sub>3</sub> solar-blind photodetectors are studied theoretically and experimentally. The results show that Al nanoparticles with a radius of <sc>30 nm</sc> can produce an LSPR effect under <sc>254 nm</sc> solar-blind ultraviolet light. Due to the LSPR effect of Al NPs, the spectral responsivity and detectivity of the β-Ga<sub>2</sub>O<sub>3</sub> solar-blind photodetector have been increased by 4.7 times and 6 times, respectively, and the dark current of the device has been reduced to 62.5% of the original value. This study provides a theoretical and experimental basis for the application of Al NPs in the solar-blind band, and provides a new method for further improving the performance of solar-blind photodetectors.