Abstract: Presents an investigation on nonlinear instability of 3D printing arch made of 3D printing material ABS-M30 under the settlement of arch foot. Based on the principle of minimum potential energy, the analytical expression of instability critical load is derived, and the distribution of arch radial displacement along the arch axis under vertical and horizontal displacements of arch foot is obtained. The loading system which is capable of controlling the settlement of arch foot is designed. Then the equilibrium path of arch in the loading process is obtained experimentally, which is verified by analytical and finite element simulation. Meanwhile, the influence of rise span ratio and slenderness ratio on the critical load of 3D printing arch is analyzed. The results show that the nonlinear instability load decreases with the increase of arch foot settlement; with a certain arch foot settlement, the nonlinear instability load increases with the increase of rise span ratio, while decreases with the increase of slenderness ratio which has the most significant effect on the nonlinear instability load.