The embodiment of the invention provides a method and a device for determining a floor where a terminal device is located. The method comprises the steps of determining a first elevation value and a second elevation value of the terminal device at a first intelligent access node at a target moment based on a preset first elevation value calculation formula and target position information when theterminal device is in a line-of-sight environment; and based on the first elevation value and the second elevation value, determining floor information of the terminal device at the target moment. According to the embodiment of the invention, in a 5G ultra-dense network, a plurality of low-cost intelligent access nodes are deployed in the indoor environment. the terminal device is in a sight distance environment, the floor information of the terminal device at the target moment can be determined only by receiving the sight distance signal sent by the terminal device and the preset first elevation value calculation formula without the air pressure value and the temperature value of the position where the terminal device and the intelligent access node are located, so that the accuracy of indoor positioning is improved.