An antenna port mapping method and a network device are disclosed. The method includes: determining, by a network device, a polarization direction of each of P physical antennas of the network device and an antenna array to which each of the P physical antennas belongs, where P is a multiple of 4; and respectively mapping, by the network device, a first antenna port and a second antenna port to a first group of physical antennas and a second group of physical antennas in the P physical antennas, and respectively mapping a third antenna port and a fourth antenna port to a third group of physical antennas and a fourth group of physical antennas in the P physical antennas.