The invention discloses a magnetic liquid sealing device suitable for high-linear-speed rotating working conditions, belongs to the field of sealing of mechanical engineering, in particular, is suitable for sealing under high-linear-speed rotating working conditions, and can solve the problems of weak pressure resistance and lower reliability when the linear speed in the rotating shaft starting process of a traditional magnetic liquid centrifugal sealing structure is lower. The device consists of a rotating shaft (1), a shell (2), a left bearing (3), a first separation magnetic ring (4-1), a first pole shoe (5-1), a first sealing ring (6-1), a first permanent magnet (7-1) and the like. When the rotating shaft (1) rotates at low linear speed, an axial magnetic liquid sealing module achieves a sealing effect; and under the condition of sufficient axial space, the number of axial magnetic liquid sealing teeth can be increased, so that the pressure resistance is improved, the sealing reliability is improved, and the problem of weak pressure resistance in the rotating shaft starting process of the traditional magnetic liquid centrifugal sealing structure is solved.