We theoretically study the influence of the spin–orbit coupling(SOC) on the in-plane optical anisotropy(IPOA) induced by in-plane uniaxial strain and interface asymmetry in(001) GaAs/AlGaAs quantum wells(QWs) with different well width. It is found that the SOC has more significant impact on the IPOA for the transition of the first valence subband of heavy hole to the first conduction band(1H1E) than that of 1L1E. The reason has been discussed. The IPOA of(001) InGaAs/InP QWs has been measured by reflectance difference spectroscopy, whose amplitude is about one order larger than that of GaAs/AlGaAs QWs. The anisotropic interface potential parameters of InGaAs/InP QWs are also determined. The influence of the SOC effect on the IPOA of InGaAs/InP QWs when the QWs are under tensile, compressive or zero biaxial strain are also investigated in theory. Our results demonstrate that the SOC has significant effect on the IPOA especially for semiconductor QWs with small well width, and therefore cannot be ignored. We theoretically study the influence of the spin-orbit coupling (SOC) on the in-plane optical anisotropy (IPOA) induced by in-plane uniaxial strain and interface asymmetry in (001) GaAs / AlGaAs quantum wells It is found that the SOC has more significant impact on the IPOA for the transition of the first valence subband of heavy hole to the first conduction band (1H1E) than that of 1L1E. The reason has been discussed. The IPOA of (001) InGaAs / InP QWs has been measured by reflectance difference spectroscopy, whose amplitude is about one order larger than that of GaAs / AlGaAs QWs. The anisotropic interface potential parameters of InGaAs / InP QWs are also determined. The influence of the SOC effect on the IPOA of InGaAs / InP QWs when the QWs are under tensile, compressive or zero biaxial strain are also investigated in theory. Our results demonstrates that the SOC has significant effect on the IPOA especially for semiconductor QWs with small well width, and therefor e can not be ignored.