The present invention discloses a channel estimation method, apparatus, and device and a multichannel microwave communications system. According to the channel estimation method, a first vector group corresponding to a transmit end and a second vector group corresponding to a receive end are first obtained according to a transmit-receive array size; then a subchannel estimation procedure is performed multiple times according to the transmit-receive array size, the first vector group, and the second vector group, to obtain multiple corresponding subchannel estimated coefficients; and finally, a real channel matrix is determined according to the first vector group, the second vector group, and an estimation matrix consisting of the multiple subchannel estimated coefficients.