The invention discloses a parallel flow hydro-cracking method. The method comprises following steps: introducing fresh raw oil into a hydro-refining reactor and a hydro-cracking reactor at the same time in a parallel-flow way; separating the reaction product, which flows out from the hydro-refining reactor, so as to obtain a light naphtha fraction, a heavy naphtha fraction, a middle fraction oil, and a tailing oil fraction; transporting all or part of the tailing oil fraction into the hydro-cracking reactor, and introducing the reaction product, which flows out from the hydro-cracking reactor, and part of raw oil into the hydro-refining reactor. The method can process heavy fraction oil and maximally produce the middle fraction oil. In the method, only the tailing oil fraction enters into the hydro-cracking reactor, thus the selectivity of the middle fraction oil is improved; part of raw oil enters into the hydro-cracking reactor, thus the phenomenon that many occurrences of secondary cracking of the middle fraction oil happen in the hydro-cracking reactor because of the over strong cracking activity of the hydro-cracking catalyst in the absence of ammonia is avoided, and the yield of the middle fraction oil is effectively increased.