The invention discloses a current-mode IPT system efficiency optimizing control circuit and method. A primary-side control circuit comprises a primary-side voltage adjustment circuit, a high-frequency inverter circuit, a primary-side compensation circuit, a primary-side coil, a primary-side current detection module and a primary side and secondary side current ratio controller. A secondary-side control circuit comprises a secondary-side coil, a secondary-side compensation circuit, a rectification and filter circuit, a secondary-side voltage adjustment circuit, a secondary-side current detection module and a secondary-side constant-voltage control module. The current-mode IPT system efficiency optimizing control circuit has the advantages that the relationship between the primary side and secondary side current ratio and system transmission efficiency is fully utilized, and the primary side and secondary side current ratio control idea is adopted for achieving the optimization of system efficiency; the current-mode IPT system efficiency optimizing control circuit is simple in structure and convenient to use; on the premise that secondary-side output voltage is stable, the current-mode IPT system efficiency optimizing control circuit ensures that the system achieves maximum-efficiency output within a wide load range through primary side and secondary side current and voltage detection and the adoption of a multi-path proportional controller.