Abstract: To get high precision of localization in WSNs (wireless sensor networks), an equilateral triangle localization algorithm based on average RSSI is brought up, taking account mainly of the measurement precision and improvement of the distribution of beacon nodes. This algorithm presents two concepts: sensitive region and insensitive region of RSSI. It introduces Gauss model to deal with the RSSI which is got from in sensitive region, then the problem that RSSI is easy to be interfered is resolved. And the equilateral triangle distribution model is used to deal with the distribution of beacon nodes to ensure that the tracks of unknown nodes are always kept within the insensitive region, thus improving the measurement precision. A conclusion is drawn that the Gauss model can screen out the first-class RSSI well and the equilateral triangle distribution model can improve the acquisition precision. This algorithm is easy to implement and no communication expense and extended hardware are required.