Layered chalcogenide materials (LCMs) are emerging materials in recent years for their great potential in applications of electronics and optoelectronics. As a member of LCMs, SnSe₂, an n-type semiconductor with a band gap of ∼1.0 eV, is of great value to explore. In this paper, we develop a facile CVD method, for the first time, to synthesize diverse shaped SnSe₂ and square SnSe nanosheets (NSs) on SiO₂/Si substrates. To the best of our knowledge, the thickness of as-grown SnSe₂ is among the thinnest ones synthesized by CVD methods on various substrates. What's more, photodetectors are fabricated to investigate the optoelectronic properties of SnSe₂. The on/off ratio of photoswitches reaches 100 under the illumination of an 800 nm laser. This work will pave a new pathway to synthesize LCM nanostructures, shed light on the shape evolution during the growth process and expand the candidates for high performance optoelectronic devices.