Hydrocracking method for increasing production of middle distillates

The invention relates to a hydrocracking method for increasing production of middle distillates. The method comprises the following steps that: fresh feedstock oils are simultaneously introduced into a hydrofining reactor and a hydrocracking reactor in a co-current flow way; a reaction effluent from the hydrofining reactor is separated to obtain light naphtha fractions, heavy naphtha fractions, middle distillates and tail oil fractions; all or part of the tail oil fractions are introduced into the hydrocracking reactor, and a reaction effluent from the hydrocracking reactor and part of the feedstock oils are introduced into the hydrofining reactor together. According to the method provided by the invention, the heavy distillates can be treated, and the maximum production of the middle distillates can be realized. Only the tail oil fractions are introduced into the hydrocracking reactor, so that the selectivity of middle distillates is improved; and part of the feedstock oils is introduced into the hydrocracking reactor, so that the phenomenon that the cracking activity of a hydrocracking catalyst is too strong, and more middle distillates are cracked secondarily in an ammonia-free environment in a hydrocracking reactor system is avoided, and thus the yield of the middle distillates is effectively improved.