The invention discloses a vortex electromagnetic wave signal modal parallel separation method based on space orthogonal transformation. The method comprises the following steps: first of all, converting each receiving array element parallel output signal of a circular array structure antenna into omni-directional vortex electromagnetic wave parallel signals with multiple modes through de-beamforming processing; then taking the signals after de-beamforming as input signals of a space orthogonal transformer in a parallel mode; the space orthogonal transformer performing the space orthogonal transformation (i.e., fast Fourier transform) about a vortex electromagnetic wave azimuth on the input signals so as to obtain modal discrete spectrum distribution of multimode vortex electromagnetic waves; and finally, outputting in parallel modal discrete spectrum components of the vortex electromagnetic waves, wherein each output component corresponding to a respective mode carries independent modulation signals, the mode of each output component is removed, and thus modal parallel separation and identification of space multimode vortex electromagnetic wave signals are realized. At the same time, the invention also simultaneously discloses a multimode vortex electromagnetic wave signal modal parallel separation apparatus based on space orthogonal transformation.