Abstract Single-molecule spin caloritronic devices, which convert the heat into electricity by using spin degree of freedom of electron, are attracting attention with the inspiration of finally shrinking electronic components by utilizing molecules as elementary blocks. In this work, one kind of molecular-scale spin caloritronic devices is theoretically proposed, which consists of a transition metal porphyrin (TM(Pr), TM=V, Mn, Fe, Co) molecule sandwiched between single-walled carbon nanotube (SWCNT) electrodes via carbon atomic chains (CACs). The corresponding spin transport properties are calculated. The results show there is robust Fano resonance in the transmission spectra around the Fermi energy for one spin component in each device, which is attributed to the quantum interference between continuous spin states originating from delocalized states over the pristine SWCNT-porphyrin device and “quasi-discrete” state mainly localized on the TM(Pr) molecule. Utilizing Fano resonance, spin-dependent Seebeck coefficients of the devices for one spin component can be strengthened. Interestingly, it is revealed the energy, spatial distributions, and parity of molecular orbitals of TM(Pr) molecules play an important role in the generation of Fano resonance, which is dependent on the kind of TM atom. Therefore, this further provides the possibility to optimize spin-dependent Seebeck coefficient by TM atoms. This work is helpful for the future design of spin caloritronic devices.