The invention relates to a hanging device for water isolating pipes and a hanging method thereof. The hanging device is characterized by comprising a shell type bracket provided with a through hole in a bottom end, a hollow hanging chuck coaxially and tightly connected to the upper end of the bracket, a plurality of hydraulic cylinders evenly hinged to the lower surface of the hanging chuck, a second hanging chuck hinged to piston connecting rods of the hydraulic cylinders and having the same structure with the hanging chuck, and a water isolating pipe string hinged on the hanging chuck and/or the second hanging chuck, wherein a plurality of pins extending in the radial direction are evenly distributed on the inner walls of the hanging chuck and the second hanging chuck; and hydraulic fluid with pressure difference are fully filled in two cavities of the hydraulic cylinders. The hanging device has such advantages as simple operation and strong operability under emergency condition.