A high efficiency power management circuit for ambient vibration energy harvesting system was designed. As the unstable ambient vibration energy and the strong load dependence, the maximum power point tracking (MPPT) technology was used. To address the problem of excessive power loss in the voltage adjustment phase during MPPT operation, a pseudo buck structure topology with a high frequency switching controller was proposed to reduce the switching loss in the voltage adjustment phase, further improving the system efficiency and enabling pre-stabilization to reduce the burden on the later stage power management. The proposed circuit was designed in a 0.18 μm CMOS process. The simulation results show that, the maximum power point tracking efficiency is maintained at 98.55%~99.45% with wide variations of the input vibration energy and the system load. And the system efficiency is improved up to 94.2%.