Abstract：The trefoil is known as the simplest nontrivial molecular knot. TheC30 carbyne trefoil knot studied is intertwined by the sphybridized(C≡C—)15 chain, which is topologically chiral and belongs to D3 point-group of symmetry. Density functional theory (DFT) calculations have been carried on the molecular knot at the RB3LYP/6-31G(D) levels. Based on the optimized geometry, the vibrational spectra, natural bond orbital (NBO) and orbital energy level analysis for C30 carbyne trefoil knot have been calculated at the same level, and compared with the cyclo-C30 carbyne molecule. The results show that the electronic structure possesses three primary attributes: C≡C nonplanar conjugated structure, inherently helical structure and highly strained crossing bonds, and the molecular orbitals are also twisted. Furthermore, the tied trefoil knot has less conjugation property and Jahn-Teller effect but higher total energy than the cyclo-C30 carbyne, that is, the process of “tied” could increase the energy of molecules.