A study of quantum confinement effects on the low-dimensional electron mobility in various AlGaAs/GaAs quantum well/wire structures has been performed. The influence of the electron envelop wave function and the subband structure on the low-dimensional electron scattering rates is evaluated. The electron transport behavior is studied through a Monte Carlo simulation. The result shows that the low-dimensional electron mobility varies significantly with the quantum well/wire geometry. The one-dimensional electron mobility of 9200 cm2/V s is obtained in a rectangular quantum wire with a geometry of 110 Å×110 Å. This value is much improved in comparison with the bulk electron mobility of 8000 cm2/V s in intrinsic GaAs and the maximum two-dimensional electron mobility of 8600 cm2/V s in a 120 Å GaAs quantum well. It is also noticed that the highest low-dimensional electron mobility is achieved in a quantum well/wire structure where the energy separation between the first subband and the second subband is about two polar optical phonon energy.