A multi-order wave voltage controlled oscillator (VCO) includes a power impedance matching unit, a signal transmitting unit, a harmonic wave eliminating unit and an oscillation frequency adjusting unit. The power impedance matching unit includes an input end, an output end and a first transmission line between the input end and the output end. The first transmission line is a ¼-wavelength transmission line based on a wavelength of an output harmonic wave. The signal transmitting unit includes multiple upper inductor electrically connected to the output end and multiple lower inductors electrically connected to a ground end. The harmonic wave eliminating unit includes multiple transistors electrically connected to the signal transmitting unit and each having a drain electrically connected to a gate of the adjacent transistor to form a multi-order ring loop. The oscillation frequency adjusting unit includes multiple varactors.