The present invention relates to a poor-quality heavy distillate oil hydrotreating method. According to the method, under a hydrorefining condition, a heavy distillate oil raw material and hydrogen gas are mixed and enter a first-stage reaction zone to carry out a hydrotreating reaction, the first-stage reaction zone effluent is subjected to gas-liquid separation to obtain a liquid phase, the liquid phase enters a second-stage reaction zone to carry out a hydrotreating reaction, and the second-stage reaction zone reaction effluent is separated to obtain the hydrotreating reaction product. Compared with the existing hydrotreating technology in the prior art, the method of the present invention has the following advantages that: the product quality and the processing capability of the device can be substantially improved, or the operating pressure can be reduced and the operating cost can be reduced under the same product quality and processing capability condition.