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Two red earth sections from the Chengdu Plain in Sichuan Province are dated using geomagnetic methods. The Brunhes/Matuyama (B/M) reversal boundary is recognized within the upper parts of the two sections, and the Jaramillo normal subzone occurs in the middle-lower parts of the vermiculated red soil (VRS), which indicate that the parent material for the VRS deposited in the middle Quaternary. Sedimentologic and geochemical studies suggest that the Chengdu Clay and part of the parent material for the VRS are of aeolian origin. Pollen analysis indicates that the Chengdu Plain was mainly covered by needle-leaved forest with a cool to cool temperate humid climate when the parent material for the VRS deposited. The relatively cool to cool temperate climatic condition in the Chengdu Plain in the middle Quaternary, which may be caused by the uplift of the Tibetan Plateau, was a response to the geo-environmental changes of global significance.