The SS Buck-WPT system composed with Buck and basic SS-type wireless power transfer circuit has been widely used in inductive wireless power transmission because of its superiority in structure, control methods and effect. However, this kind of system can"t meet the requirements of time-varying system in responsiveness due to its poor dynamic characteristics. For example, the system in filed applications has large overshoot and oscillation when starting up, alteration on system stability for the various load resistance and sharp fluctuation of primary resonance current under light condition. To address those dynamic problem, a SS-type Buck-WPT system based on controllable inductance was proposed in this paper. First of all, controllable inductance was analyzed in detail to figure out the principle of adjustable inductance and modeled in COMSOL to verify the conclusion. Then the Mathematical modeling analysis of SS Buck-WPT system was carried out. Taking SS WPT system as the load of Buck, the system state space equation was derived. And the system was described with two-dimensional phase trajectories by reducing dimensionality. Then the phase trajectory operation law during start-up was proposed and pre-Buck circuit was improved by changing conventional inductor to controllable one and controlling the inductor via to make system get in stable in one turn-on without any overshoot; The output voltage will be different that goes back and forth once load changes. So, the PI algorithm is used to keep current constant, so that the phase trajectory runs as expected, and the output of secondary returns to the steady state quickly with the real-time control of inductance ; For the excessive primary resonant current, the controlled inductance cascaded with SS in primary to maintain it’s current within permissible values by adjust inductance automatically. To validate the performance of proposed method, the prototype is set up in Simulink. The results show that this strategy has better effect on system dynamic performance and loads tolerance compared with traditional one.