Abstract: Indoor localization utilizing wireless technology is becoming an eager interest of research community in recent years. To provide location aware service, obtaining the position of a user accurately is important. The fingerprint localization based on received signal strength (RSS), is a radio map of the area by measuring the power present in a received radio signal, which don’t require the additional hardware cost. However, utilizing RSS for localization has a number of limitations. For example, the fingerprint localization algorithm generally faces the multipath and shadow interference caused by the physical blocking in the practical application. This paper analyzes how the physical blocking to change the signal strength in fingerprint algorithm, and finds that the line of sight(LoS) fingerprint instead of the original fingerprint can avoid the emergency of shadow and reduce the multipath influence. Based on above analysis, we propose a line of sight fingerprint-based localization algorithm (LoSF). Since the line of sight fingerprint has the abnormal values, we design an error processing algorithm to eliminate errors in the fingerprint data. Compared with the existing algorithms, the performance of LoSF algorithm achieves a median error of 2m, much less than the 6m of RADAR algorithm based on the original fingerprint, and less than the half of the COMPASS algorithm with 4.2m precision.