The invention discloses a multi-impeller passive rotary stirring type open caisson rotary drill bit. The multi-impeller passive rotary stirring type open caisson rotary drill bit comprises a hollow drill pipe, a drill bit body, a cutting edge, an impeller shaft, passive impellers and a rotary bracket. The multi-impeller passive rotary stirring type open caisson rotary drill bit is mainly used fordrilling pouring construction of a reverse circulation drilling machine on a bridge middle tower open caisson, by evenly distributing the four sets of impellers around the drill bit body, in the working process of the drill bit body, the impellers make contact with the hole walls, relative rotation in the direction opposite to the rotation direction of the drill bit body is passively generated, thus in the drilling process, full mixing of silt and water is accelerated to form mud, and the stirring effect of the drill bit body on the mud is enhanced in the drilling process. Under the situationwithout increasing of additional power, the mud discharge efficiency in the drilling process is improved, thus the drilling efficiency is improved, and the situation that in the drilling process, dueto unsmooth silt discharging, a mud sucking pipe is blocked, and the drill bit is silted up and even broken is avoided.