The magnetic coupling wireless power transfer (MC-WPT) technology has gained extensive attention due to its convenience and safety. However, single-module MC-WPT systems are limited by switch devices, passive devices, and cost, making it difficult to meet the requirements of high-power applications. The modular series-parallel approach is a common solution to increase the capacity of the system for high-power scenarios. Under high power, full-load operation of the primary-side multiple modules increases the equipment stress of the secondary-side modules, thus reducing system reliability. To address this issue, this paper proposes an adaptable modular secondary-side multi-module expansion architecture. During operation, this architecture achieves voltage equalization among the secondary-side modules and allows for flexible module insertion and removal without affecting other modules. An 8.6kW MC-WPT system with three primary-side modules and three secondary-side modules was established to verify the equalization characteristics and module switching capability of the proposed architecture.