The invention discloses a mechanical looseness-prevent drilling machine stand column. According to the mechanical looseness-prevent drilling machine stand column, the length of the stand column can be conveniently adjusted, a spring can be prepressed, and stability is high. According to the technical scheme, according to the structure of an outer stand column assembly, an outer stand column body is fixed to a base through a bolt, a supporting seat is of a concave structure, an outer thread is arranged on the upper portion of a screw rod, a stepped shaft is arranged on the lower portion of the screw rod, the operation end of a power mechanism penetrates through the side face of the outer stand column body and is located outside the outer stand column body; and according to the structure of the inner stand column body, a lifting column is installed in an inner cavity of the outer stand column body, the lifting column is a column-shaped shell with holes in the upper end and the lower end, the screw rod is inserted from the lower end of the lifting column correspondingly, the lower end of a guide rod is connected with the upper end hole of the lifting column through a thread, the guide rod and the lifting column are locked into a whole through a locking nut, a butterfly spring is installed on the guide rod in a sleeving mode, an inner stand column body is a reversed concave structure, a through hole is formed in a top isolation plate of the inner stand column body, and the guide rod in a T shape is inserted from the trough hole of the isolation plate of the inner stand column body and clamped in the isolation plate of the inner stand column body.