A method of channel estimation enhancement is provided. In a wireless communications system, a transmitting device transmits a long preamble frame comprising a first training field, a signal field, and a second training field. The signal field has a beam-change indicator bit indicates whether there is beam change between the first training field and the second training field. A receiving device receives the long preamble frame, performs a first channel estimation based on the first training field, and performs a second channel estimation based on the second training field. If the beam-change indicator bit indicates negative beam change, then the receiving device performs channel estimation enhancement by combining the first channel estimation and the second channel estimation. As a result, channel estimation performance is improved.