Take VD furnace’s shell as research object, using ANSYS FEM study its stability character. The furnace body and cover’s 3D and FE model were established separately. Model’s eigenvalue buckling were analyzed at 20°C and 200°C , on the basis of this, considering structure’s initial disfigurement and material’s nonlinearity, furnace body and cover’s double non-Linear Buckling Load under external pressure were calculated. The result shows that furnace body’s double non-Linear Buckling Load are 1.44 MPa and 0.96 MPa at the normal temperature and 200°C separately, and its appeared 7 wave-number’s lateral instability; The furnace cover’s double Non-Linear Buckling Load are 2.07MPa and 1.23 MPa at the normal temperature and 200°C separately, maximum displacement on the roof and near vacuum duct position. The furnace body and cover’s stability under 20°C and 200°C satisfied design requirements. The calculate results provide the theory basis for VD vacuum furnace’s physical design.