According to the Harrison's model, the level change of conduction and valence bands caused by the strain of AlInGaAs/AlGaAs quantum well (QW) was analyzed firstly. The energy level of the electron and hole in the AlInGaAs/AlGaAs strained and GaAs/AlGaAs unstrained QW were calculated, respectively. In addition, taking the lorentzian function, the linear gain of the two QWs were calculated and discussed. Contrast the gain performance of GaAs/AlGaAs QW with that of AlyInxGa1-x-yAs/AlGaAs QW, it can be found that the strained AlyInxGa1-x-yAs/AlGaAs QW material has more promising optical gain than that of the GaAs/AlGaAs QW.