A wireless detection device is provided, comprising a voltage control oscillation unit, a transceiving unit, demodulation unit and processing unit. The voltage control oscillation unit generates different oscillation signals according to analog control voltages and corresponding injection signals. The transceiving unit outputs first wireless signals to a predetermined area according to the oscillation signals and receives second wireless signals generated by reflection of the first wireless signals to generate the injection signal. The demodulation unit demodulates the oscillation signals into first voltage signals. The processing unit subtracts the corresponding analog control voltages from the first voltage signals to generate second voltage signals, and when the variation of the second voltage signals exceeds a predetermined value on a target frequency in frequency domain, the processing unit calculates a real distance between an object and the transceiving unit.
