3D–Printed concrete (3DPC) at early-ages often collapses during the printing process owing to insufficient buildability, which affects continuous printing. To correctly simulate the buildability of early-age 3DPC, a finite element (FE) model with the Drucker–Prager (D–P) model reflecting the fundamental concrete material properties was proposed. The yield criterion, flow, and hardening rule of the D–P and the Mohr–Coulomb (M–C) models were comparatively analyzed. A nonlinear stress–strain relationship was selected to describe the mechanical behavior of early-age 3DPC. Uniaxial compression tests, hollow cylinder, and straight wall printing tests were used to calibrate and verify the simulation results. The predicted peak stress in uniaxial compression tests and the elastic buckling of straight walls agree with the test results. The predicted error of the plastic collapse of the hollow cylinder with the D–P model decreased by 13.8% compared with that of the M–C model. Finally, the feasibility of the D–P model is demonstrated and discussed.