Static yield stress is the most vital rheological parameter affecting the printability of concrete for additive manufacturing technologies based on layered extrusion. According to the theoretical analysis on the relationship between the static yield stress and the concrete composition, the components of 3D printable concrete (3DPC) can be divided into paste phase and aggregate phase. Within this context, the influence of paste composition and aggregate content on the static yield stress of 3DPC was investigated in this research. It is found that the static yield stress of 3DPC is proportional to the static/dynamic yield stress of its corresponding paste and the aggregate content, separately. Additionally, it is proved that the flowability of paste significantly depends on its static/dynamic yield stress, no matter which type of rheological modifier agents is applied. Based on the experimental results, a modified Coussot model was established to predict the static yield stress of 3DPC, allowing for the flowability of paste and the thickness of excess paste layer as crucial parameters.