Since the single-sided linear induction motors (SLIMs) for rail transit usually works with an asymmetric air-gap, the degrees of primary-secondary coupling attitude are the key variables for the electromagnetism and force characteristics in the motors. Therefore, this paper investigates the influences of the primary-secondary coupling attitude on the characteristics, e.g., secondary impedance, induced eddy current, and electromagnetic forces, by using the numerical method. First, a 3-D analysis model used for finite element method is established, and the configurations for the three basic attitudes are given. Second, the map of the induced eddy current on the secondary under the three basic attitudes are given. Third, three-dimensional electromagnetic forces and secondary parameters are obtained based on the results of electromagnetic field quantities.