The invention discloses a WPT system signal transmission device based on a parasitic parameter. The WPT system signal transmission device comprises a primary side coil and a secondary side coil which are used for realizing energy transmission, and a signal generation device and a signal receiving device which are used for realizing signal transmission, wherein a primary side metal plate and a secondary side metal plate are correspondingly arranged on the two sides of the primary side coil and the secondary side coil; the primary side coil and the secondary side coil are planar coils and are opposite to the primary side metal plate and the secondary side metal plate, so that parasitic capacitance is generated between every two of the primary side metal plate, the primary side coil, the secondary side coil and the secondary side metal plate; the signal generation device and the signal receiving device realizes wireless signal transmission by the parasitic capacitance. The WPT system signal transmission device has the beneficial effects of low cost, easiness in implementation, high transmission rate, high reliability and the like, and higher sensitivity and higher space position offset redundancy can be realized.