Provided in the present invention is a motion mechanism applied to a mobile terminal of a flexible screen. The motion mechanism comprises a left side rotating arm, a right side rotating arm and a fixing base, wherein the left side rotating arm and the right side rotating arm are respectively connected to a virtual circle center rotating connecting structure, and the virtual circle center rotating connecting structure uses an arc guide groove and an arc sliding block structure; the arc sliding block is arranged at an end of the rotating arm; the fixing base is provided with a bottom floating block; the arc guide groove is divided into an upper portion and a lower portion at the bottom of the groove, the upper portion being arranged in the fixing base, the lower portion being arranged on the bottom floating block, and the upper portion and the lower portion forming the arc guide groove; and the bottom floating block and the fixing base are elastically connected in a direction perpendicular to the reference plane. According to the present invention, it can be ensured that an arc guide rail and an arc sliding block can slide without a clearance; in addition, jamming caused by too small of a clearance can be prevented by means of a proper back-off, so that the space is guaranteed and the amount of Z-direction shaking is also eliminated, thereby solving the problems of shaking and jamming caused by tolerance accumulation.