The self-assembly behavior of H1-BCz, a first-generation dendrirner with phenyl-carbazole as core and carbazole as dendrons, was systemically studied by solvent-vapor annealing. The morphologies of spin-coated H1-BCz film on various substrates changed from giant crystalline fibers of several millimeters to spherulites with a decrease in tetrahydrofuran vapor pressure. At high vapor pressure, dewetting easily took place in the amorphous films, and single fibers or fiber clusters formed. The fibers grew from nuclei formed at the place where it does not dewet. The fibers grew larger by continuous nucleation and growth at the growth front of the fiber until all the substance on the substrate was consumed. As the vapor pressure decreased, dewetting did not so easily happen, and fibers packed more tightly and spherulites were obtained. Through characterization of the crystals and films, we speculate that 3D H1-BCz crystal formed by overlapping 2D lamellar structure. The pi-pi interactions and van der Waals interactions among H1-BCz molecules and solvent may be the main force driving the self-assembly of H1-BCz.