A proximity detection method implemented by a detecting device includes: (a) receiving detection signals from multiple signal providing devices that include a target device and at least one reference device; (b) for each of the detection signals, collecting signal strength values of the detection signal at a variety of time points; (c) filtering out a portion of the signal strength values based on a predetermined criterion; (d) for each of the detection signals, calculating a signal level according to a sum of the signal strength values; and (e) calculating proximity of the target device in relation to the at least one reference device according to the signal level.