The invention discloses a load bearing type mechanical arm, which comprises a hydraulic driving pump, wherein the hydraulic driving pump is connected with a directional mechanism; the directional mechanism is connected with a tail end executer, and comprises a main hydraulic flow passage; the main hydraulic flow passage is connected with at least two branch flow passages and a pressure leakage bypass; a pressure regulating valve is arranged in each branch flow passage; the branch flow passage comprises a first flow section, a second flow section and a third flow section in sequential and serial connection arrangement from the liquid inlet end to the liquid outlet end; the inner wall of the first flow passage is provided with a screw thread groove; the second flow section is in an ellipsoid shape; a pressure regulating valve is arranged in the second flow section; a third flow passage comprises a plurality of arc-shaped sections in tangential connection; the tangential line included angle between the inlet and the outlet of each arc-shaped section is smaller than 30 degrees; the tail end of each branch flow passage is connected with a piston rod; the piston rod is hinged to the tail end executer. The load bearing type mechanical arm has the advantages that the defects in the prior art are overcome; the driving mechanism is simplified, and the positioning capability of the mechanical arm is improved.