Abstract: Based on the molecular type homologous series matrix, a structure oriented lumping (SOL) method was established to simulate molecular composition of residue, where 65 single cores and 12 multi-cores assumed structure were chosen as the seed molecules which were divided by carbon number of the side chain, resulting in 3 749 kinds of virtual molecules to represent the residue molecular compositions. Each molecule was composed of 15 kinds of basic structure vectors to represent the reaction process of molecules and to calculate the individual properties. With the structural attribute distributions of the residue, the mole fractions of each molecule can be confirmed, and the bulk properties were derived from the calculated mole fractions and the individual properties. Therefore, the mole fractions were determined based on the parameters of the attribute distributions by simulation annealing algorithm. As the results of 3 kinds of residual samples show that the calculated values of bulk properties of residue are in accordance with the measured ones, the distribution of the molecular weight reveals obvious gamma distribution for relative molecular mass of each residue aromatics. It is feasible to represent the residue with the 3 749 kinds virtual molecules, and the method based on the structural attribute distributions can well be used to calculate the mole fractions.