The invention discloses a manually digging hole full-
steel cylinder-wall protecting construction device for a building
pile foundation and a construction method thereof. The device comprises a working chamber, an orifice protection joint, a full-
steel cylinder protecting dilation joint and a lifting bracket, wherein the working chamber has an inverse
barrel shape, the orifice protection joint is a T-shaped sleeve, and the full-
steel cylinder protecting dilation joint is a cylinder which is formed by mutually screwing three steel templates. The construction method comprises the following steps: firstly, manually digging a hole, putting the working chamber into the hole, and then putting the orifice protection joint into the hole; secondly, putting the full-steel cylinder protecting dilation joint into the hole, screwing off a bolt to increase the
diameter, making the full-steel cylinder protecting dilation joint support the wall of the hole, filling gaps by filling steel sheets, and downwards digging the hole and circularly putting the full-steel cylinder protecting dilation joint into the hole till digging to a designed depth; and screwing down the bolt for the down-most full-steel cylinder protecting dilation joint after finishing, lifting the full-steel cylinder protecting dilation joint out of the hole through the lifting of a
winch, by
inference, lifting all the full-steel cylinder protecting dilation joints out of the hole, finally withdrawing the working chamber, then putting the orifice protection joint into the hole, and pulling out the orifice protection joint when the
pile foundation concrete is poured. The construction device and the construction method are safe to use and high in working efficiency.