Recent years have witnessed a rapid development of the preparation methods for aggregation structures and have witnessed a continuous expansion of the application areas, which afford the opportunity to construct molecular devices with smaller size, stronger function and better performance. The organic conjugated molecules based on pi system have attracted an increasing attention as a novel unit for the building of nanostructures. In this paper, beginning with the introduction of the concept and characteristic of nanomaterials, we discuss the construction methods for supramolecular functional materials based on organic pi-conjugated and inorganic/organic hybrid systems. For organic pi-conjugated system, the methods include vapor deposition, template and classic self-assembly. For inorganic/organic hybrid system, the methods include sol-gel, intercalation, blending, template and supramolecular self-assembly. Among these methods, we focus on the classic self-assembly one for organic system. In the process of self-assembly, several driving forces have important influence on the aggregation morphologies, including pi-pi stacking, hydrogen bonding, electrostatic interaction, dipole-dipole interaction, metal coordination, hydrophilic and hydrophobic interactions. Although in this process, one or two driving force predominate, several driving forces are involved actually. On the basis of the preparation of nanomaterials, we discuss the construction of functional molecular devices and their wide applications in the fields of field emission, photoelectric detection, solar cells, sensors, nonlinear optical and optical waveguide materials.