In electromagnetic field subdomain analysis, the dimension of the coefficient matrix is the main factor affecting the solution speed. To further improve the solution efficiency, this article takes an axial-flux induction planar motor that compensates tangential forces generated by tilting of deployable mechanism in spacecraft ground test as the research object and proposes an improved subdomain (IP-SDM) solution model based on reduced order coefficient matrix. Using the equivalent current method, the reduced order coefficient matrix is realized by reducing the number of subdomain layers. The effect of eddy current is considered in the solution process, and the air gap magnetic field distribution and electromagnetic force under sinusoidal current excitation are calculated. Compared with the traditional subdomain methods, the solution speed of the IP-SDM model has been improved. To further prove the efficiency of the proposed method, the air gap magnetic field distribution and horizontal electromagnetic force are investigated by changing the parameters affecting the eddy current. Finally, the accuracy of the proposed IP-SDM model is verified by finite element analysis and prototype experiments.