We report the study of the magnetoresistance behavior and the charge/spin modulations in a high quality single crystal of SrFeO3-δ using magnetization, conductivity, and x-ray scattering. The crystal displays a sharp magnetic transition at T ≈ 60 K and a nonlinear conductivity behavior at about T ≈ 110 K, suggesting a 3-δ of about 2.81. In addition, there exists the hysteresis phenomenon with a transition width of about 10 K at T ≈ 60 K. A charge modulation was located at (0, 0, L ± q), q ≈ 0.36 to have a transition temperature of T ≈ 110 K by the use of x-ray scattering with x-ray energy of 10 keV and 12 keV. This is in accord with the nonlinear transport transition as observed by conductivity measurement. By the means of resonant soft x-ray diffraction around the Fe L-edge, we also observed the spin modulation (from paramagnetic to antiferromagnetic states) in agreement with the formation of spin ordering doubling the c-axis.