The invention relates to a heavy oil hydrogenation method and a hydrogenation system. The heavy oil hydrogenation method comprises the steps of mixing heavy oil, circulation oil, a valcanizer and a catalyst, performing hydrocracking on the heavy oil, the circulation oil, the valcanizer, the catalyst and hydrogen in a first reactor to form a first reaction product, allowing part of first reaction product to return to the first reactor, performing hydrocracking on the rest of the first reaction product in a second reactor to form a second reaction product, dividing the second reaction product into a light component and a heavy component, returning part of the heavy component to the second reactor, separating the rest of the heavy component to form distillate oil as the circulation oil, and hydrofining the light component in a third reactor to form a light oil product. The method improves heat transfer and mass transfer efficiency, ensures retention time of the material in the reactors, and increases a heavy oil conversion rate and a light oil yield. According to the hydrogenation system for the method, internal members of the reactors are simplified, and equipment investment and operation energy consumption are reduced.