This paper analyzes several conditions of received signal strength indication (RSSI) indoor node localization based on experiments. An RSSI indoor propagation model is established using an indoor wireless communication model and the measured data. Different positioning precision of the unknown nodes in different locations are compared. The particle swarm optimization (PSO) algorithm is used to optimize the locating results. Experimental results show that the PSO algorithm has good performance. The influence of different number of beacon nodes is analyzed for the node positioning accuracy. The experiment shows that the beacon node number affects the positioning accuracy to a certain extent. When there are too many beacon nodes, reliable ones should be chosen as to ensure the localization precision.