Abstract In this thesis, We have probed the semiconductor microstructure by photoreflectance. A laser beam was used to modulate the dielectric constant and the parameter £GR and R were probed with a white light source. First, we perform measurement and simulation for a single quantum well structure grown by molecular beam epitaxy(MBE).Three subband transition can be found in our simulation, and a 2D third derivative model was used to fit experiment data. For the absorption coefficient and refractive index, we perform a simulation with a ideal model ( i.e. FWHM=0). In the simulation, we can understand that the photoreflectance spectrum is composed with symmetric and anti-symmetric line shapes in our fitting model. In addition, we can observe FKO effect in this sample and obtain electric field from FKO data. For asymmetric InGaAs/InGaAlAs multiple-quantum wells, we perform measurement, simulation and curve fitting for both modulation doping and non-modulation doping samples. We can observe many high order sub-band transitions. Besides, some quantum well signals for the modulation doped samples were not observed due to the cancellation of build-in electric field.