Full-mechanical rotary steering drilling tool

The invention discloses a full-mechanical rotary steering drilling tool which comprises a mandrel, a first bearing pack, a lower bearing seat, a pushing piston, a piston seat, a lower torsional spring, an upper bearing seat, a second bearing pack, an upper mandrel connector, a staggered moving ring piece, a shaft moving piston, an upper connector, a limiting ring, a filtering ring, an upper spring, a third bearing pack, a weighting block, an outer barrel, an impeller, an upper disc valve, a lower disc valve and a fourth bearing pack. Electronic components are not used, the problems that an existing rotary steering drilling tool is insufficient in high-temperature resistance, electronic components are prone to damage, and consequently a drilling tool fails are solved, and the drilling requirements under the high-temperature and high-pressure working conditions of a deep well can be met. In addition, an eccentric weight stabilizing mechanism and a flow control impeller disc valve torsion mechanism are further a