Abstract: In order to find the appropriate quantum well number, the electrical and optical characteristics of InGaAsSb/AlGaAsSb laser diode with various QW numbers and contents were investigated using LASTIP simulation program. In the case of single QW, the total number of carriers injected into the QW will be small and the radiative recombination will be poor. When the number of QWs was increased into larger than 4, however, the optical performance started to degrade because of the uneven distribution of carrier concentration and the higher electron concentration in the p-side, which increased in the internal loss in the active region. Taking into account of the effect of QWs number on the epitaxy layers quality, the optimized number of InGaAsSb/AlGaAsSb 2 m LDs was 2-3. The obtained results are beneficial to the design of the high performance 2 m Sb-containing LDs.