The high temperature traps of AlGaAs/GaAs GRIN-SCH SQW lasers fabricated by MBE has been studied using DLTS technique.The majority and minority carrier DLTS spectra show that high temperature trap, having larger capture cross section and concentration, exist in n-AlGaAs layer of lasers. This trap may correlate strongly with oxygen content of AlGaAs layer grown by MBE. It may be responsible for the degradation of laser performance. High temperature hole trap may spatially localize between the interface of xAl= 0.2→0.43 and xAl= 0.43 n-AlGaAs layers. And high temperature electron trap may spatially localize in the interface regions of discontinous variation Al mole fraction of AlGaAs layer with xAl= 0.43.