A new type of AlxGa1-xAs/GaAs beterojunction based on Si δ-doping has been fabricated by MBE method. We measured the magnetoresistances, mobility and Hall resistance of the 2-D electron gas at the junction in a transvers magnetic field from 0.3 to 30K. Using Fourier-transform analysis, the distribution of electrons and their effective masses for each subband are determined. which are ｍ0*／ｍ0＝０．０７３，ｍ1*／ｍ0＝０．０６８. With the decreasing of temperature，the electrons in each subband increase continuously. We observed abnormal peaks in magnetoresistance wben magnetic field was scanned from 0 to 7T at 0.3K.