The authors collected 263 orientated samples at an interval of 20~25 cm from the “red clay” sequence. The magnetic remanence was measured with a 2G-760 U-channel system in the Institute of Geology and Geophysics, Chinese Academy of Science. In addition, the authors measured the carbon isotopic composition of 46 carbonate nodules in order to constrain the paleomagnetic polarity, since a significant C4 plant expansion at 4 Ma is well documented in the “red clay” sediment on the Loess Plateau. The δ13C record indicates a major expansion of C4 plants at the depth of 3 m. The combined results from magnetostratigraphy and isotope stratigraphy demonstrate that the polarity zones of the Jungar Banner section correlate with those between C3n.1r and C3An.2n of the GPTS, yielding an age range of 4.13~6.61 Ma and a relatively constant sedimentation rate of 2.52 cm/ka.