Taking InGaAs/GaAs strained quantum wells as an example,the 6×6 Luttinger-Kohn Hamiltonian considering the valence band mixing and the wave function mixing,and by using the finite-difference method to solve the Luttinger-Kohn Hamiltonian of the effective mass equation are introduced. Then the conduction-band structures and the valence-band structures are obtained. The transition matrix element of strained quantum well,and the material gain with linear Lorentzian function are also calcuated. Finally the well width,carrier concentration,temperature and other factors which influence the gain material are discussed. The results show that the compressive strain makes the effective quantum well bandgap increase,reduces the transparency of the material gain current density,and then lower the threshold of the device to improve the output characteristics of the device. The right deviation between the gain peak wavelength and the emission wavelength make optically pumped semiconductor laser′s threshold current and operating current have small changes in temperature.