The invention discloses an integrated hydrate down-hole in-situ separation parallel-connection device with the large treatment capacity. The problems that in the mining process of hydrates, sand production is serious, and existing separators are low in separation efficiency are mainly solved. The integrated hydrate down-hole in-situ separation parallel-connection device comprises a top short section, parallel-connection assemblies, a bottom assembly, a lower plug and an outer pipe which are connected in sequence, wherein the multiple parallel-connection assemblies can be mounted simultaneously, or no parallel-connection assembly is mounted, the parallel-connection assemblies each comprise a parallel-connection short section, a backfill pipe, a separator and an inner pipe which are connected in sequence, and the bottom assembly comprises a bottom short section, a backfill pipe, a separator and a bottom inner pipe which are connected in sequence. According to the integrated hydrate down-hole in-situ separation parallel-connection device, the multiple separators are connected into an integrated outer pipe string in parallel, and the large treatment capacity is achieved while the separation precision is ensured; and the multiple separators are connected in parallel in a hydrate mining pipe string, the working capacity of the separators is greatly improved, the problem of the largesand production amount of the mined hydrates is solved, sand backfilling is ensured, the situations that reservoir collapse occurs, the pipe conveying efficiency is lowered, and equipment abrasion iscaused are prevented, and the mining cost of the hydrates is lowered.