Abstract. Aiming at the construction stage of off-line fingerprint database of fingerprint positioning technology based on WiFi, for the construction of traditional fingerprint database needs field acquisition of fingerprint signal widely, it is difficult to achieve in a large area, a method is proposed to construct the fingerprint database based on optimal attenuation factor model. Firstly, the traditional attenuation factor model was optimized, the free space model and the attenuation factor model were combined, and through the signal acquisition of several nodes, it realized the self-adaption of the path loss index in attenuation factor model. Secondly, the method of constructing the fingerprint database by using the optimized attenuation factor model was given. Finally, the optimization is confirmed by simulating with a variety of classical propagation model.