Three-dimensional space coordinate system establishment method based on true north of earth

The invention discloses a three-dimensional space coordinate system establishing method based on the true north of the earth, which comprises the following steps of: firstly, acquiring an observation pillar geodetic coordinate of an antenna system mounting area, and acquiring a basic workpiece datum point of an antenna system as a coordinate system origin O; measuring geodetic coordinates and Gaussian coordinates of the reference point, and establishing a reference surface of a coordinate system; calculating a geodetic azimuth angle gamma between the original point O and the pointing point A; then taking O as an original point of the coordinate system, enabling a Z1 axis to be vertically upward along the point O and perpendicular to the reference plane P, enabling an X1 axis to point to a point A, enabling a Y1 axis to be determined by a right-handed coordinate system rule, and establishing a reference coordinate system O-X1Y1Z1; and finally, anticlockwise rotating around the Z1 axis by an angle gamma, and at