The prevent invention provides a method for preparing deuterated chemicals, and deuterated chemicals. The method comprises the step of: making halides undergo a deuteration reaction with a deuterium source under the catalytic action of a light source and a photocatalyst, to obtain deuterated chemicals, wherein the deuterium source is deuterium oxide or a deuterated solvent, and the reaction temperature is between -80°C and 150°C. By using a more environmentally-friendly and cheaper deuterium oxide or deuterated reagent as a deuterium source instead of a deuterium gas, halides can be deuterated under the photocatalytic action of a photocatalyst, such as Ru and In metal catalysts, organic dyes, and inorganic and organic semiconductor nanomaterials, and therefore, the present invention can precisely and controllably prepare a series of deuterated chemicals. Compared with conventional deutration reactions, the present invention has higher selectivity, milder reaction conditions, wider substrate adaptability and higher economic applicability, and is expected to be applied to large-scale production of deuterated chemicals.