The band gap and carrier concentration of ternary tin dichalcogenides can be continuously controlled by changing the sulfur and selenium contents, which has large application potential in electric and photoelectric devices. In this paper, SnSxSe2-x (x=0, 0.2, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0) single crystal nanosheets were controllably prepared by chemical vapor deposition (CVD) technique. The prepared SnSxSe2-x nanosheets were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The results prove the controllable preparation of SnSxSe2-x nanosheets with adjustable elemental percentages in high monocrystalline quality. The elemental percentage dependence of the Raman spectroscopy from SnSxSe2-x nanosheets were especially studied, and the experimental results are well consistent to the simulation results by first-principles calculation based on the density functional theory. This study provides a reliable method for the preparation of ternary SnSxSe2-x single crystal nanosheets with adjustable elemental percentages. A definite and nondestructive method for the characterization of ternary tin dichalcogenides is also proposed.