A water-chemical route to synthesize copper phthalocyanine (CuPC) is reported in this paper. The molecules were self-assembled into regular beta-CuPC single-crystal nanobelts simultaneously. The molecular structure of CuPC in the nanobelts was characterized by UV-vis absorption spectroscopy, MALDI-TOF-MS, and elemental analysis. The morphology and crystal phase of the nanobelts were investigated by electron microscopy and X-ray diffraction, respectively. Crucial factors for the formation of CuPC nanobelts were also investigated. The cooperative effect of the surfactant and copper powder was important for the formation of CuPC. The CuPC nanobelts were obtained through a self-assembly process. In addition, a phase transition process, which resulted in the formation of beta-CuPC single-crystal nanobelts, took place with prolonged time.