The invention aims to provide a foreign matter detection method for an LC series topology wireless charging system. The method is relatively low in hardware cost, high in reliability and relatively high in precision. The method comprises the following steps that: step 1, in a primary power-on calibration stage, after power-on, the natural resonant frequency f, the quality factor Q and the equivalent direct current resistance of an LC network of a transmitting end are calculated, and recorded as common parameters; and 2, the output current If of a coupled current sensor is collected in real time, and the effective value Uf of the input voltage of an excitation source and the current working frequency f1 of the excitation source during sampling are recorded, the parameters are substituted into a quality factor change rate conversion formula, so that the change rate of the quality factor Q caused by the intervention of metal foreign matters is to calculated,if the change rate of the current quality factor Q is smaller than a set metal foreign matter detection judgment threshold value, an alarm is given, and charging is stopped, and if the change rate of the current quality factor Q is within the set foreign matter detection judgment threshold range, a charging system is safe, and charging is continued.