Molecular simulation technology is widely applied in the research of polymer materials because it can re-veal the relationship between macro properties and micro structure of polymer materials.However

in molecular simu-lation

the influence of molecular numbers on the properties of cross-linked epoxy resin system is rarely involved.Reasonable selection of molecular number in the system has a certain effect on the reasonable and accurate construc-tion of cross-linked molecular models

which will further affect the properties of epoxy resin system. From the per-spective of molecular simulation

based on COMPASS molecular filed

cross-linked epoxy resin models with differ-ent molecular numbers（the number of DGEBA molecules are 24

32

40 and 48 respectively）were built using Materi-als Studio

which was used to analyze the effect of molecular number on the properities of the cross-linked epoxy resinsystem. Micro structural parameters

such as the energy

fraction free volume and the mean square displacement andmechanical properties including the bulk modulus

shear modulus

Young’s modulus were calculated of cross-linked epoxy resin systems with different molecular numbers in the paper

comparing the changes energy

fraction free volume

MSD and modulus in different systems. The preliminary results indicate that with the increase of molec-ular numbers

the total energy of cross-linking system is basically unchanged and the total volume increase. Whenthe DGEBA molecules are 40 in the cross-linked epoxy resin system

the bulk modulus and Young’s modulus of thecross-linked system are the largest

and the shear modulus is slightly lower than that of the system containing 24 DGEBA molecules.The comprehensive mechanical properties are better than those of the other 3 systems.