The paper gives a mechanical and history analysis on the characteristic of Laojunshan meta-morphic core complex in southeastern Yunnan and its structural environment, and considers that metamorphic core complex is actually a nuclear column of a vortex structure, which was caused by the Wenshan-Malipo strike-slip fault. Later extensional detachment strengthened uprising of the metamorphic core complex. The significance lies in that the paper puts forward the rotation-shearing genesis of metamorphic core complex, which can rationally interpret that the formation of Viet Bac old landmass is due to the collision between Indo plate and Yangtzi plate and the rotation-shearing uplift due to the strike-slip movement of the Red River fault and Wenshan-Malipo fault.