On the basis of two novel range-free positioning algorithms named DV-Hop improved algorithm and APIT improved algorithm are proposed for three-dimensional wireless sensor networks based on traditional DV-Hop algorithm and APIT algorithm.The DV-Hop improved algorithm makes the unknown nodes only accept anchor information of local area by setting reception threshold in nodes.The APIT improved algorithm replaces grid scanning by tetrahedral centroid scanning.Principles of the two algorithms are introduced

simulations are carried out.The simulation results demonstrate that in 100m×100m×100m three-dimensional space

communication node radius is 30m and anchor node ratio is more than 25%

relative positioning error of the two algorithms can both reduce to below 30%.