Wireless charging technology provides a convenient and safe method for electric vehicles. To meet the needs of commercial operations, it is essential to accurately measure the active power at the transmitter end of the wireless charging system. However, due to the high-frequency and high-voltage, measuring the voltage at the transmitting coil is challenging. In response to this issue, this paper focuses on the bilateral LCC compensation network and analyzes the harmonic components of the current and voltage at transmitting coil. It derives the voltage relationship between compensation capacitor and the transmitting coil and indirectly measure voltage at transmitting coil, finally proposing an active power calculation method for the transmitting coil. An experimental prototype of a wireless charging system utilizing bilateral LCC compensation is built. Simulations and experiments verify that the active power consumed by the transmitting coil is mainly the fundamental component, and the impact of the sampling frequencies and power levels on the measurement accuracy is discussed.