Abstract: Biostratigraphical, lithostratigraphical and magneto?tratigraphical restudies of Yuan- niou formation (in broad sense) show that the boundary between the Shagon formation of Pliocene and Yuanmou formation (in narrow sense) of lower Pleistocene is situated at the limit of Matuyama/Gauss Epoch about 2.48 m.y, (B.P.) and the boundary bet> ween the latter and the Shangnabang formation of middle Pleistocene is situated at the limit of Brunhes/Matuyama Epoch about 0.73 m.y. (B.P.).
According to a reexamination of the paleomagnetic polarity of Yuanmou section? it is easily to find that there is an evident polarity reverse in the 13th layer of the 2nd member up to the 23rd layer of the 3rd member of the section ,that covers in a thickness about 300 m. Then, it follows more than 100 m in thickness of the 4th member with normal polarity, i.e., the Shangnabang formation. So, it might be appropriate to correlate this normal polarity member as the Brunhes Epoch but not to a certain normal polarity event of the Matuyama Epoch. If so? a fully different explanation on the magnetostratigraphy of Yuanmou formation could be reached that the layer which yielded the fossils of uYuanmou man?, is magnetostragraphically situated at the base of the Brunhes Epoch and the age of "Yuanmou manM might be not older than 0.73 m.y. (B.P.), possibly 0.5—0.6m.y. (B.P.), but not 1.3一1.7 m.y. (B.P.).

Key words: Age of "Yuanmou man"; Dating; Middle pleistocene