Two-dimensional (2D) organic semiconductor crystals are single crystal materials grown by self-assembly using intermolecular van der Waals forces. The intrinsically single crystal properties make it possess excellent electrical properties. More importantly, the enhanced interfacial properties in the 2D limit can greatly tune the device behaviors, providing the possibility to construct multifunctional interfacial devices. In addition, the exposed charge transport channel and few in-plane defects make it possible to study the intrinsic transport properties of organic electrons. At present, great progress has been made in the growth process of two-dimensional organic semiconductor crystals, however, the theoretical study of the self-assembly process of two-dimensional crystal growth is still very scarce. In this work, two-dimensional organic semiconductor crystals were successfully prepared by additive-assisted crystallization technology, the surface morphology and structure of the two-dimensional crystals were comprehensively characterized by polarized light microscopy and atomic force microscopy. For the mechanistic study of crystal growth, the SEM combined with EDS techniques were employed to study structural and compositional characterization of key nucleation interfaces. The results show that the growth material can nucleate stably at the additive interface, and it is calculated that the favorable interface constructed by the additive can reduce the nucleation barrier to 1/5 of that on the SiO2 interface. This work fully demonstrates the key role of the growth interface in crystal growth, and theoretically reveals the regulated behavior of the interface, that provides a reliable idea for the growth process design of two-dimensional organic semiconductor crystals.