Low-temperature electrical properties of the two-dimensional electron gas (2DEG) in delta-doped In0.1Ga0.9As/GaAs strained single quantum wells were studied by Shubnikov-de Haas (S-dH) and Van der Pauw Hall-effect measurements. The results of the capacitance-voltage profile indicates that the full width half-maximum value of the delta-doped In0.1Ga0.9As/GaAs quantum well is 45 angstroms. The angular dependent S-dH measurements at 1.5 K demonstrated clearly the existence of a quasi-2DEG in the In0.1Ga0.9As single quantum wells, and the fast Fourier transformation results for the S-dH data clearly indicate the electron occupation of three subbands in the delta-doped In0.1Ga0.9As/GaAs strained single quantum wells. The electronic subband energies, the energy wavefunctions, and the Fermi energy in the In0.1Ga0.9As/GaAs strained single quantum wells were calculated by a self-consistent method taking into account exchange-correlation effects together with the strain and nonparabolicity effects. These present results can help improve understanding for the potential applications of delta-doped In0.1Ga0.9As/GaAs strained single quantum wells in new kinds of the promising electronic devices.