A method for determining a time difference of arrival, and a communication device and system, where neighbor cells for positioning are determined for a target terminal by a positioning server, then cell identities of the neighbor cells and beam polling configuration information of the neighbor cells are transmitted to the target terminal, so that the target terminal may detect a Positioning Reference Signal (PRS) beam transmitted by a corresponding neighbor cell according to the beam polling configuration information, and a time difference of arrival of PRS beams transmitted by one neighbor cell and another neighbor cell is calculated.