Nowadays, Cu2SnS3 is emerging as a promising solar cell material because of its suitable optoelectronic properties. Large-grained Cu2SnS3 thin films are highly desirable to realize high efficiency in Cu2SnS3-based solar cells. The deliberate addition of impurities into the absorber is an appropriate approach to fabricate large grained absorber layers. Hence, we have doped a pentavalent antimony (Sb) into Cu2SnS3 films via chemical bath deposition of SnS/Sb2S3/CuS stacks followed by annealing in a graphite box. The effects of annealing temperature and annealing duration on the grain growth of Sb-doped CTS films is discussed in detail. Owing to its surfactant property, Sb-doping promotes a layer-by-layer growth mode and results in uniform, compact, and large-grained Cu2SnS3 films with grain sizes of 5 mu m. Thus, Sb-doping assisted the crystal growth, to produce large-grained Cu2SnS3 thin films, which can provide a new path-way to enhance the device efficiency of Cu2SnS3-based solar cells.