Abstract: A method for lining a manhole: (i) inserting into the manhole a tubular liner wet with a curable liquid resin; (ii) everting an inflatable plastic bag into the tubular liner by charging water in it; (iii) closing the open end of the everted bag to form a closed space inside the bag; (iv) supplying compressed air to the closed space to cause the plastic bag to inflate and press the liner against the manhole; and (v) curing the liquid resin to harden the liner; and further improvements include: plugging the main pipe with two plugs to isolate the manhole and stop the drain from wetting the manhole, but providing a hose penetrating through the plugs to allow the drain to flow past the manhole; partially filling the portion of the main pipe isolated between the two plugs with a liquid absorbent filler; the tubular liner has varied thickness increasing toward its lower end stepwise or continuously and has its lower opening covered up by a net attached to the lower end circumference of the liner.