Abstract: Based on the studies of stratigraphic sections, contact relationship, regional correlation and isotopic dating, the rock association of variegated polymictic conglomerate, pebbly sandstone with volcanic rocks in the lower part of previous Manketouebo Formation developed in the Daxinganling Mountains is re-assigned to Upper Jurassic Tuchengzi Formation, which is well compared with that in Yanshan-Liaoning region. The confirmation of the Tuchengzi Formation fills the blank in the study area. The research on the forming time of the Tuchengzi Formation and the contact with the overlying formation will provide evidence for the Mesozoic stratigraphic division and correlation in the Yanshan-Liaoning area, and supply reference to the study of Mesozoic geological evolution in Daxinganling region.