It was found that increasing the number of anchor points in non-line-of-sight (NLOS) channels may worsen NLOS path effects, ultimately degrading system performance. To improve the accuracy of ultra-wide band (UWB) indoor positioning in three-dimensional space, this study proposes a particle swarm optimization (PSO) algorithm that incorporates anchor weight adjustments. By using this anchor-weighted PSO approach, the study found that the proposed method effectively reduces positioning errors caused by NLOS conditions, thereby enhancing the accuracy and practical applicability of UWB systems in complex environments.