The present invention discloses a poor-quality heavy distillate oil hydrocracking method. According to the method, poor-quality heavy distillate oil and hydrogen gas enter a first-stage reaction zone to carry out a hydrorefining reaction, the reaction effluent enters a separator to separate, the obtained liquid enters a second-stage reaction zone to carry out a hydrorefining reaction, the second-stage reaction effluent and supplement hydrogen gas are mixed and then enter a third-stage reaction zone to carry out a hydrocracking reaction, and the hydrogenation reaction effluent is subjected to separation and fractionation to obtain various hydrocracking products. With the method of the present invention, the nitrogen-containing impurities in the poor-quality raw material can be subjected to hydrotreating under the relatively mild condition so as to make the poor-quality raw material meet the hydrocracking feeding requirement, such that the hydrocracking raw material source is broadened; and the hydrorefining temperature is substantially reduced so as to increase the operation period of the device and process the poor-quality raw material, or increase the processing capacity of the device in the same operation period.