The lower accuracy of hot spot temperature estimation on microprocessors can lead to a higher probability of false alarms and unnecessary responses, which results in a reduction of the reliability of computer systems. In this paper, an improved thermal reconstruction method based on dynamic Voronoi diagram with non-uniform sampling on multicore processors has been proposed. Experimental results indicate that the proposed method significantly outperforms spectral analysis techniques in both thermal reconstruction error and hot spot temperature error. It can be better applied in dynamic thermal management techniques to achieve global and local thermal monitoring.