Effects of the number of quantum wells (QWs) and Shockley-Read-Hall (SRH) recombination in deep-ultraviolet (DUV) light-emitting diodes (LEDs) are investigated theoretically. Simulation results show that, for DUV LEDs with high crystalline quality, light output power increases with an increasing number of QWs. As for the DUV LEDs with poor crystalline quality, light output power may decrease with an increasing number of QWs due to the deteriorated SRH recombination. The injection current density is also an important factor regarding the impact of the number of QWs. When operated at low current density, for the DUV LED with poor crystalline quality, light output power may decrease with an increasing number of QWs.