The invention discloses a magnetic soft screen door with the adjustable horizontal fixed size. The magnetic soft screen door comprises a soft screen door main body and a top edge fixing assembly usedfor fixing the top edge of the soft screen door main body. Magnetic strips are arranged on the inner side of the soft screen door main body at intervals, and connecting rods are arranged between the magnetic strips; the top edge fixing assembly comprises a base plate and an extending-retracting assembly fixed to one side of the base plate in a retractable mode; the extending-retracting assembly comprises a guiding strip, a locking strip and a locking rod; and the base plate comprises a main body part and a separating part, and the main body part is fixed to the top of a door frame through fixing blocks. Compared with the prior art, the magnetic soft screen door is provided with the extending-retracting assembly, and thus the distance between the main body part and the separating part is adjusted, so that the magnetic soft screen door adapts to the door frames of different sizes, and the application range of the magnetic soft screen door is enlarged accordingly.