We present a dipole-dipole interaction model based on the classical electrostatic theory in the Langmuir-Blodgett (LB) films to calculate the state of aggregation of rod-like molecules with permanent electronic dipole moment. The dependence of the molecular aggregation spectral properties on the structure parameters in the Z-type LB films, such as the intra-layer molecular separation distance, the adjacent layer separation distance, the molecular orientation angle and the layer number of LB films have been studied. It is found that the H-J-type transition of the aggregation could be realized by modulating the structure parameters of the LB films. The theoretical results show a qualitative agreement with experimental data. (C) 2007 Elsevier B.V. All rights reserved.