Bismuth oxychloride (BiOCl) single crystal nanosheets with controllable and highly exposed {001} facets have been synthesized via hydrolytic methods without any surfactants. The BiOCl nanosheets had a thickness from 30 to 120 nm and were synthesized by tuning evaporation temperature, while the ratio of {001} facets varies from 98 to 49%. A growth rate in {001} facets agrees with the Boltzmann function and a possible growth mechanism has been proposed. Moreover, the existence of highly exposed {001} facets could gradually narrow the band gap of BiOCl nanosheets. This work provides a new insight for controllable synthesis of layered materials with different facets, and provides a flexible strategy for exploring and enhancing photoactivity based on the facets engineering. [GRAPHICS] .