Abstract: A speed estimation method including a reference value establishing step, an actual value establishing step, an approximate location calculating step, a weight location calculating step, a weight location determining step and a speed calculating step is disclosed. The reference value establishing step determines a plurality of training locations and establishes a reference signal strength set for each training location. The actual value establishing step establishes an actual signal strength set of a communication device at a time point. The approximate location calculating step calculates a plurality of signal strength differences according to the actual signal strength set and the reference signal strength set, and generates a plurality of approximate locations. The weight location calculating step calculates a weight location of the communication device. The weight location determining step determines whether two weight locations are obtained.