Localization technology is one of the key technologies in Wireless Sensor Network (WSN). The Centroid algorithm, DV-HOP algorithm, APIT algorithm and Amorphous are the classic algorithms which are based on Range-free localization algorithm. This paper is improved on the basis of the DV-HOP and Weighted DV-HOP node localization algorithm, proposed an improved DV-HOP and weighted DV-HOP of WSN localization algorithm based on Simulation Curve Fitting (SCF). The SCF algorithm makes the process more refined during selecting the beacon node and the selected beacon node can be closer to the accurate position.