As a formwork-free construction method, 3D concrete printing has great freedom in forming structures thus attracts wide attention in construction industry. However, the form-work free feature also poses challenges for its construction. Without the support of formworks, the lower layers should have the capability to resist its self-weight and the gravity load generated by the deposition of the upper layers. Thus, the buildability of 3D-printed concrete (3DPC) is worth attention and is studied by peridynamics (PD) in the present paper. The constitutive relations are incorporated in by bond-based correspondence model to describe the mechanical behavior of 3DPC. And the layer-wise particle activation and time-dependent material properties growth are conducted to reproduce the 3D concrete printing process. This develops an accurate numerical scheme for buildability modeling and is then verified by deformation modeling of a hollow cylinder as well as the failure mode prediction of a square wall. The simulation results show that the proposed method is able to model the basic features of buildability in 3DPC and thus can help to design 3D concrete printing processes.