In this work, structural properties of the imidazole cured epoxy-phenol resins were theoretically simulated by the Monte Carlo (MC) procedure. The proposed procedure can be extended to any other complicated reaction system. The structural properties, including the epoxide conversion, the weight average molecular weight, the sol-gel fraction, the number average branch point of the sol part, the branch as well as the loop density of the gel part were discussed. The theoretical results were further verified experimentally by differential scanning calorimetry (DSC), sol extraction test, and gel permeation chromatography (GPC). The theoretical results agree with the experimental data quite well. (C) 2001 Elsevier Science Ltd. All rights reserved.