The ultraviolet AlGaInN light-emitting diode under study is grown on a c-face sapphire substrate by low-pressure horizontal-flow metalorganic chemical vapor deposition (MOCVD). With increasing input current from 10 to 100 mA, the main peak of the emission wavelength shifts from 368 to 372 nm. The room-temperature output power is 0.8 mW at 20 mA. Under continuous-wave operation, an output power of 4 mW is achieved at a driving current of 125 mA. The simulation program, advanced physical model of semiconductor devices (APSYS), is used to fit in our experimental results in order to obtain an optimized structure. The device performance affected by piezoelectric and thermal effects is studied via drift-diffusion model for carrier transport, optical gain and loss. The optical performance of the ultraviolet light-emitting diodes with different numbers of quantum wells at various temperatures is numerically investigated. Preliminary simulated results indicate that when the number of quantum wells is 5 to 7, better output performance is obtained. To raise the internal efficiency and radiative recombination rate, a current blocking layer SiO2 is used to guide and confine current flows through active region.