Abstract: Multipath propagation can significantly reduce the TDOA-based accuracy. In this paper, a beam steering circular polarization antenna (BSCPA) is used to mitigate indoor multipath propagation. The BSCPA consists of a beam switch network, four identical hexagon patch elements and their feeding networks. By controlling the states of a radio frequency (RF) switch in the beam switch network, four steering circular polarization beams can be excited separately for azimuth omnidirectional coverage. Depending on steering beams and circular polarization of the BSCPA, the positioning inaccuracy from indoor multipath propagation can be mitigated. In a line of sight (LOS), complex multipath indoor environment with the areas of 10. 8 m×6. 6 m, the 2D positioning mean error obtained is 0. 71 m with a 20MHz bandwidth signal in WLAN. Compared with conventional omnidirectional linear polarization antenna (OLPA), the BSCPA can improve positioning accuracy by 52. 5%. The improvement shows that the proposed method can significantly mitigate multipath propagation for TDOA-based indoor positioning.