Abstract: Applying parameter identification technology, the secondary side parameters of wireless power transfer (WPT) systems, such as the load parameters, can be obtained without the wireless communication and sensors. It will benefit the WPT control and condition monitoring. This article presented a WPT multiple parameter joint identification method. Through this method, joint identification of the battery voltage, charging current, rectifier equivalent input impedance, secondary side voltages and currents was achieved, based on only one primary side measured voltage without knowing the coil coupling state in advance. First, an equivalent circuit model of WPT system was established to get the independent relationship between the voltage across the primary side parallel compensation capacitor and the secondary side impedances. Then, piecewise linearization of the rectifier equivalent input impedance was adopted, and the stray resistances of the WPT secondary side compensation capacitors were ignored. These methods can simplify the identification algorithm while ensuring the accuracy. Furthermore, the quantitative relationships between the WPT measured variables and identified parameters were deduced. Meanwhile, the specific identification process and steps were described. Finally, an experimental platform was developed and the experimental results indicate that under the conditions of the varied load and different coil coupling, the maximum identification errors of the battery voltage, charging current, rectifier equivalent input resistance, reactance, secondary side voltage and current are 5.5%, 5.2%, 6.4%, 6.5%, 7.9%, and 6.9%, respectively. Therefore, the proposed method can achieve relatively high accuracy, and it is suitable for the WPT working conditions of varied load and varied coupling.