Contactors are widely used switching devices in power systems. To address the accuracy limitations of traditional single-step iteration methods under small air-gap conditions, this study presents a novel field-circuit decoupled simulation approach for analyzing contactor dynamic characteristics. This method, developed on the Simdroid static electromagnetic simulation platform, integrates multiple iteration techniques. Three distinct electromagnetic iteration methods are employed: the conventional differential iteration method, a predictor-corrector scheme based on Runge-Kutta method (developed autonomously), and a differential iteration method incorporating local interpolation. The conventional single-step differential iteration offers high computational speed but lower accuracy. The interpolation-enhanced differential iteration achieves higher accuracy at the cost of reduced speed. The predictor-corrector method provides a balance between accuracy and computational efficiency. At each simulation timestep, an adaptive criterion selects the most appropriate iteration method based on the current conditions. The selected method is then executed, and the results are output. Validation results demonstrate excellent agreement with simulations performed in Maxwell, with deviations consistently below 10%. This confirms the effectiveness of the proposed method as a robust computational approach for simulating electromagnetic dynamics in contactors.