A novel molecular distance-edge vector with 6 parameters was calculated for 100 polycyclic aromatic hydrocarbons (PAHs) based on the molecular interaction theory. It was found that there was a good linear relationship between the molecular distance-edge vector (VMDE) and the gas chromatographic retention index for the 100 PAHs, and the molecular modelling equation for the quantitative structure-retention relationship (QSRR) can be expressed as follows: IR = a + b VMDE, n = 100, r = 0.988, where a and b represent regression coefficients. The regression results showed that the molecular distance-edge vector is in good agreement with the results of molecular polarizability index to the gas chromatographic retention index for the polycyclic aromatic hydrocarbons.