Provided is a convenient assembly anti-wave metal net cage for open seas. The metal net cage comprises one net cage floating frame or more, each net cage floating frame is formed by floating shelf corner units, a floating shelf middle unit, a handrail, floating shelf connecting members, floating shelf fixing members and floating bodies; adjacent net cage floating frames are connected by flexible connecting members; the floating shelf unit includes a double-row tube, and one end of the double-one tube is welded with the floating shelf connecting member, the other end of the double-row tube is acoincident portion, the floating shelf middle unit includes a double-row tube, and both ends of the double-row tube are welded with the floating shelf connecting members; the four corners of the netcage floating frame are composed of two mutually perpendicular floating shelf corner units, and the coincident portions are fixed by the floating shelf fixing members, and the floating bodies are installed between the two parallel circular tubes of the double-row tubes; each net cage floating frame is connected with the flexible connecting members to form a net cage group. The net cage is used inthe open areas, is convenient in transportation, the size of the net cage can be assembled according to needs, and the convenient assembly anti-wave metal net cage connected by the novel net cage flexible connecting members is particularly suitable for the open seas or island and reef sea areas in Southern China Sea far away from the mainland.