Abstract: By means of high resolution research of rock magnetic records and quartz sands from Maogou section in the Linxia basin,we reveal that after a relative stable environment between 13.07 and 8.6 Ma, the basin was gradually influxed by eolian dusts at about 8.6 Ma, and the fluxes of eolian dusts got two rapid increases at about 6.4 Ma and 5.3 Ma respectively. The study suggests that the drying of northwest China began at 8.6 Ma and was strengthened rapidly at about 6.4 Ma and 5.3 Ma.