An auxiliary pressure device for stress urinary incontinence, comprising: an expansion body with a structure for insertion into the vagina, including a first state before insertion into the vagina, and a second state after insertion into the vagina; an adjustment system for releasing the first state of the expansion body to reach the second state of the expansion body; and a force application part connected to the expansion body, with a traction structure for the user to apply force to move the expansion body out of the vagina; wherein the expansion body comprises at least two lead-out portions evenly distributed along the circumferential direction, the respective lead-out portions being connected at roots and free at distal ends thereof, wherein the adjustment system is configured to release the first state of the expansion body to reach the second state, wherein in the first state, the distal ends are close to or fit with each other under the action of external force, and wherein in the second state, the external force is released and the respective distal ends are separated from each other under the action of the adjustment system; wherein the force application part is connected to the connection of the roots of the respective lead-out portions; wherein the expansion body is an integral structure, the connection of the roots of the respective lead-out portions is capable of acting as an additional fitting point with the vaginal wall, and the connection of the roots of the respective lead-out portions is realized through a smooth structure; wherein the connection of the roots of the respective lead-out portions forms a new fitting position in a state in which the expansion body rotates to an extreme position on one side in the vagina, thereby limiting further rotation, and in which the extrusion force of the fitting position formed by the connection of the roots of the respective lead-out portions on the vaginal wall is smaller than the extrusion force of the fitting positions formed by the distal ends on the vaginal wall; characterized in that the adjustment system is a set of like-pole permanent magnets arranged in one-to-one correspondence with the distal ends and fixedly arranged relative to the distal ends; wherein the like-pole permanent magnets are respectively embedded in the distal ends of the respective lead-out portions. an expansion body with a structure for insertion into the vagina, including a first state before insertion into the vagina, and a second state after insertion into the vagina; an adjustment system for releasing the first state of the expansion body to reach the second state of the expansion body; and a force application part connected to the expansion body, with a traction structure for the user to apply force to move the expansion body out of the vagina; wherein the expansion body comprises at least two lead-out portions evenly distributed along the circumferential direction, the respective lead-out portions being connected at roots and free at distal ends thereof, wherein the adjustment system is configured to release the first state of the expansion body to reach the second state, wherein in the first state, the distal ends are close to or fit with each other under the action of external force, and wherein in the second state, the external force is released and the respective distal ends are separated from each other under the action of the adjustment system; wherein the force application part is connected to the connection of the roots of the respective lead-out portions; wherein the expansion body is an integral structure, the connection of the roots of the respective lead-out portions is capable of acting as an additional fitting point with the vaginal wall, and the connection of the roots of the respective lead-out portions is realized through a smooth structure; wherein the connection of the roots of the respective lead-out portions forms a new fitting position in a state in which the expansion body rotates to an extreme position on one side in the vagina, thereby limiting further rotation, and in which the extrusion force of the fitting position formed by the connection of the roots of the respective lead-out portions on the vaginal wall is smaller than the extrusion force of the fitting positions formed by the distal ends on the vaginal wall; characterized in that the adjustment system is a set of like-pole permanent magnets arranged in one-to-one correspondence with the distal ends and fixedly arranged relative to the distal ends; wherein the like-pole permanent magnets are respectively embedded in the distal ends of the respective lead-out portions.