The invention discloses a flower-like cobalt sulfate photocatalyst and a preparation method thereof, the flower-like cobalt sulfate photocatalyst is prepared from an inorganic cobalt salt and a sulfur-bearing compound by means of simple hydrothermal reaction; the preparation method has the advantages of simplicity, high efficiency, good environmental friendliness, controllability, low cost and the like; the flower-like cobalt sulfate prepared herein as high stability, large specific surface area and high photocatalytic activity.