For developing novel high strength materials, we study the crystal structures, electronic properties and mechanical properties of hcp-C3 carbon bulk rings based on the first principles method. Electronic structure analysis shows that the viable sp3 hybridization appears in this carbon allotrope. It caused the mechanical properties of the carbon bulk ring to exhibit strong orientation dependence. Along the [0001] orientation, the carbon bulk ring demonstrates an elastic modulus of 1033 GPa, a Tensile strength of 124.17 GPa, and a compressive strength of 381.83 GPa. Furthermore, along the [2110] orientation, the compressive strength reaches 458.34 GPa, which shows the excellent mechanical properties of hcp-C3 carbon bulk rings.