The p-AlGaN/AlGaN superlattice (SL) hole injection structure was introduced into deep ultraviolet (DUV) light-emitting diodes (LEDs) to enhance their performances. The period thicknesses of the p-Al_0.8Ga_0.2N/Al_0.48Ga_0.52N SLs affected the performances of the DUV LEDs. The appropriate period thickness of the p-Al_0.8Ga_0.2N/Al_0.48Ga_0.52N SL may enhance the hole injection of DUV LEDs. Therefore, compared with the reference LEDs, the DUV LEDs with the 10-pair Al_0.8Ga_0.2N (1 nm)/Al_0.48Ga_0.52N (1 nm) SL presented forward voltage reduction of 0.23 V and light output power improvement of 15% at a current of 350 mA. Furthermore, the 10-pair Al_0.8Ga_0.2N (1 nm)/Al_0.48Ga_0.52N (1 nm) SL could slightly suppress the Auger recombination and current overflow of the DUV LEDs in a high-current operation region. In addition to improved carrier injection, the DUV LEDs with the p-Al_0.8Ga_0.2N/Al_0.48Ga_0.52N SL hole injection structure showed reduced light absorption at their emission wavelength compared with the reference LEDs. Therefore, the DUV LEDs with p-Al_0.8Ga_0.2N/Al_0.48Ga_0.52N SL may exhibit better light extraction efficiency than the reference LEDs. The enhancement of p-Al_0.8Ga_0.2N (1 nm)/Al_0.48Ga_0.52N (1 nm) SL may contribute to improvements in light extraction and hole injection.