A new type of light-contact electroreflectance(LCER) spectroscopy technique was proposed.The measurement of the modulation spectroscopy can be simplified by using this method.The structure of the sample holder was presented in detail.The required amplitude of modulation voltage can be largely reduced by comparing with that of CER and the mechanism is analyzed qualitatively.The experimental results in InGaAs/GaAs quantum well samples by using LCER technique are presented and indicate the high spectral sensitivity and high spectral resolution of LCER.Compared with the experimental results of photoreflectance(PR),it is shown that both spectra of LCER and PR coincide with each other and the experimental results are not influenced by the light contact between the surface of the sample and the electrode.It is concluded that LCER is an effective and convenient method for the study of semiconductor materials and semiconductor quantum wells.