The invention provides a multi-antenna decoding circuit. The multi-antenna decoding circuit comprises two antennas, two matched circuits, two non-coherent envelope detection circuits, a division operation circuit and a threshold value comparison circuit; each antenna is connected to one non-coherent envelope detection circuit through one matched circuit; the two non-coherent envelope detection circuits are connected to the division operation circuit; the division operation circuit is connected to the threshold value comparison circuit; the threshold value comparison circuit is used for being connected to a load end; the matched circuits are used for filtering signals received by the antennas, so that the antennas and the load end are in conjugated matching; the non-coherent envelope detection circuits are used for following envelop of signals output by the matched circuits, and eliminating the carrier frequencies of the signals; the division operation circuit is used for dividing voltage output by the two non-coherent envelope detection circuits, and obtaining output voltage; and the threshold value comparison circuit is used for comparing the output voltage with reference voltage, and outputting high level or low level.