The atomic and molecular assembly processes on the surface of two-dimensional (2D) layered crystals have gained significant research interest for fabrication of well-ordered nanostructures and vertical heterostructures based on 2D crystals. The structure and quality at the 2D heterointerfaces have great influence on the properties and performance of heterostructures. Therefore, the direct observation of the interfacial structure of 2D heterostructure can provide insight for understanding the fundamental aspects of the system and can also lead to a better design of a new 2D heterostructure. In this seminar, I will present various oriented self-assembly phenomena on 2D crystals. Advanced transmission electron microscopy (TEM) techniques are utilized to elucidate the atomic-scale structure of assemblies and their relative epitaxial relations with respect to 2D substrates. For example, one-dimensional metal-cyanide atomic chains exhibit universal oriented van der Waals epitaxy on various 2D crystals. I will also discuss the unidirectional assembly phenomena on various distorted 2D crystals, namely black phosphorus (BP) and distorted transition metal dichalcogenides (TMDCs). These atomically puckered 2D crystals can induce the unidirectional assembly along the directions of the crystal distortion. Finally, various electrical and optical properties of these hybrid heterostructures will be discussed.