The photovoltage spectra of GaAs/AlGaAs multiple quantum wells (QMWs) in which the substrates are semiinsultion GaAs have been studied at temperatures ranging from 18 to 300 K. A series of distinct excition absorption peaks were observed. At low temperature, the photovoltage spectra reflect the steplike distribution of state density of QMWs. It is believed that the photovoltage spectroscopy is an effective technique for inspecting the growing quanli-ty of QMWs and superlattice. The changes of photovoltage with temperature and the mechanism of photovoltaic effect are also discussed.