The BiOCl photocatalysts are synthesized via a soft chemical method with different drying temperatures. It is discovered that the drying temperatures lead to the change in the crystalline phase, morphology, surface area and optical property, playing very important roles in photocatalytic activity. Moreover, it is also found that the photocatalytic activity of BiOCl nanosheets is strongly dependent on the drying temperatures used, and the BiOCl sample dried at 120 °C has the highest photocatalytic activity. This high activity is mainly attributed to photogenerated holes and hydroxyl.