Provided is a hydrocarbon oil hydrotreating method, comprising the following steps: (1) injecting hydrogen into the hydrocarbon oil via an opening having a nanoscale average diameter, so as to obtain hydrocarbon oil containing hydrogen; and (2) under a liquid phase hydrotreating condition, feeding into a reactor the hydrocarbon oil containing hydrogen to contact a catalyst having a hydrogenation catalysis effect. The method of the present invention can quickly and efficiently disperse and dissolve the hydrogen into the hydrocarbon oil even without the aid of a diluent or circulating oil, so as to obtain stable hydrogen-containing hydrocarbon oil with a high hydrogen content, and obtain an hydrotreating effect equivalent to or even better than the existing hydrotreating methods.