Installing method for outdoor fire hydrants

The invention discloses an installing method for outdoor fire hydrants. The installing method is characterized by including the following steps that before the outdoor fire hydrants are installed, the inner walls and the outer walls of pipes are coated with asphaltic base oil twice, the outer walls need to be additionally coated with heat-regenerative asphalt twice and coated with finishing coat once, flange connectors buried into soil are coated with asphaltic base oil twice, hot asphalt needs to be additionally added into the outer walls twice, finishing coat needs to be additionally added into the outer walls once, and the outer walls are closely packaged with asphalt linen; iron pieces in fire hydrant chambers are also coated with hot asphalt for corrosion prevention; pebbles with the particle size of 20 mm to 30 mm are used as a permeable layer of dewatering outlets of outdoor fire hydrants, the laying radius is 500 mm, and the laying thickness is from 100 mm underground to the groove bottoms; the height