The dependence of the bandgaps of strained superlattice and quantum wells on uniaxial stress is studied, by using of the method of electron reflection and interference. The quantitative relation between the stress and the energy levels of GaAs-AlGaAs superlattice and quantum wells is obtained. Furthermore, the dependence of the energy levels in conduction band on uniaxial stress is calculated for GaAs-AlGaAs-GaAs. Then the dependence of absorption wavelength on the uniaxial stress is given in a quantum well infrared photodetector (QWIP). The results show that the absorption peak moves nearly 1.1 μm when the stress is increased to 1.3 GPa and the change with stress is basically linear. The peak of absorption wavelength can be tuned from 5.57 μm to 4.46 μm continuously in QWIP.