Following the previous study [Chemistry Letters 2007, 10, 1278.] on specific electron transport pathway in porphyrin, the electron transfer through oligomeric porphyrin molecular wires was studied in this work using first principle density function theory and non-equilibrium Green’s function calculations. The effects of chain length on the transportation behavior were discussed in terms of the electronic structures and transmission spectra. Through the analysis of spatial distribution of molecular frontier orbit we found that with the chain length increased, the whole delocalization of molecular frontier orbit enlarged, so e-transitivity became better. The results demonstrated that the frontier orbital energy gap decreased when the chain length increased, so that it should be conductive to electronic transmission. We presumed that the oligomeric porphyrin can be used to make moleculer electronic devices.