Aiming at the uncertainty of the offset angle of the receiving coil relative to the transmitting coil in the magnetically coupled resonant wireless power transfer (MCR-WPT) system, which leads to large fluctuations in the transmission efficiency of the system, a method for calculating the offset angle of the receiving coil in MCR-WPT system based on the reflection impedance is proposed. According to Kirchhoff’s voltage law, the relation between the reflection impedance of the transmitting coil and the mutual inductance of two coils is established, then the relation equation of the mutual inductance and the coil offset angle is derived according to the mutual inductance formula of two coils. Therefore, the expression for the reflection impedance and the offset angle is derived. The coils model and peripheral circuits are built using Maxwell and Simplorer simulation software for co-simulation. Meanwhile, a MCR-WPT experimental system is built, and multiple sets of experiments are conducted under different coil distances. The simulation results show that the mean absolute error between the set angle of two coils and the calculated angle is 2. 57°. The experimental results show that the aforementioned mean absolute error is 2. 94°. The offset angle of the receiving coil of the short-distance wireless power transmission system can be calculated accurately through the above method.