The invention discloses a device for expanding a maxillary dental arch through automatic force application. The device comprises a support, force application rods, a driving mechanism and a guide mechanism, wherein the force application rods are slidably connected with the guide mechanism, the guide mechanism and the driving mechanism make the force application rods horizontally move towards the outer side or the inner side of the support, the guide mechanism is fixedly arranged on the support, the output end of the driving mechanism is connected with the force input ends of the force application rods, the force application rods are arranged at the two sides of the support, and the guide mechanism and the driving mechanism make the force application rods horizontally move towards the outer side or the inner side of the support; and the guide mechanism comprises a guide rail and a guide sliding block, and the sliding block is slidably arranged on the guide rail and is also connected with the output ends of the force application rods and the output end of the driving mechanism. Automatic force application of an arch expander can be achieved, and the situation is avoided that the treatment progress and effect are influenced due to poor compliance of a patient; force application parameters can be adjusted according to the condition of the patient, and the comfort of the patient in the treatment process can be improved through single small-distance and high-frequency force application; and improvement from traditional maxillary arch expansion to high implementation rate increase is achieved to ensure the clinical arch expansion effect.