The utility model provides a circle flange joint device based on alternating axis helical gear nut mechanism of screwing for connect first round flange and second round flange, connecting device includes clamping ring nut, worm, worm mount and sets up the external screw thread on first round flange lateral surface, the medial surface of clamping ring nut is provided with that internal thread, lateral surface are provided with the skewed tooth, a tip is provided with the clamping ring, clamping ring nut emboitement is outside first round flange and second round flange, and the internal thread of clamping ring nut constitutes the screw pair with the matching the external screw of first round flange, the worm mount links firmly with the second round flange, the worm passes through the worm mount installs in the clamping ring nut outside, and the worm is vice with the helical gear cooperation constitution alternating axis helical drive of clamping ring nut, the clamping ring is used for compressing tightly the flange face of second round flange. Utilize the utility model discloses when inside waveguide is fastened to large -scale antenna, need not not connect alright the realization of complete set interconnected system upset level and locking, the processing ease, the devoid of risk, it is efficient.