A floating mechanism (30) comprises a lift arm (33), a translation arm (37) and a connection frame (349). One end of the lift arm (33) is rotatably connected to the connection frame (349) which is also rotatably connected to the translation arm (37). The lift arm (33) drives the translation arm (37) to rotate and move up and down between two intersecting planes with a fulcrum at the other end of the lift arm (33) opposite to the translation arm (37). The translation arm (37) can also be translated in a translational plane intersecting the lift arm (33) with the connection point of the translation arm (37) and the connecting frame (349) as an axis. The lift arm (33) and the translation arm (37) of the floating mechanism (30) can together drive an operating panel (50) to move up and down in a vertical plane and to translate front and back, and left and right in a translation plane； meanwhile, the operating panel (50) can be driven to rotate in the translation plane along with the lift arm (33) and the translation arm (37). Also provided are an ultrasonic diagnostic apparatus (100) with the floating mechanism (30) and a floating support method.L'invention concerne un mécanisme (30) flottant comprenant un bras (33) de levage, un bras (37) de translation et une structure (349) de liaison. Une extrémité du bras (33) de levage est reliée de façon rotative à la structure (349) de liaison qui est également accouplée de manière rotative au bras (37) de translation. Le bras (33) de levage amène le bras (37) de translation à tourner et à se déplacer vers le haut et vers le bas entre deux plans sécants avec un point d'appui au niveau de l'autre extrémité du bras (33) de levage, en regard du bras (37) de translation. Le bras (37) de translation peut également être translaté dans un plan de translation intersectant le bras (33) de levage avec le point de raccordement du bras (37) de translation et la structure (349) de liaison comme axe. Le bras (33) de levage et le bras (37) de t
