<p>Due to the shrinkage upon heating, when low-temperature shrinkage fibers (LTSFs) are incorporated into concrete, the shrinkage stress may be transferred to the cement matrix through the interfacial bonding, thus producing three-dimensional prestress on concrete. Therefore, LTSF has great potential in reducing temperature-induced cracking in bulk concrete. However, the evolution of microstructure and stress transfer mechanism in LTSF/cement composite (LTSF/CC) are not well understood, and there is a lack of effective and low-cost methods to characterize the prestressing effect of LTSF on cement matrix. The primary aim of this study is to explore the use of dielectric technology to analyze the prestressing effect of LTSF in cement, establish the relationship between prestressing and dielectric parameters, and understand the mechanism of LTSF to apply prestressing to cement. To this end, dielectric testing and digital imaging techniques are utilized to assess the prestress and microstructure of LTSF/CC specimens. It was found that the prestress of LTSFs exerts compressive effects on LTSF/CC, effectively closing microcracks and enhancing the compactness of the matrix. The microstructural changes within cement caused by prestress result in a strong correlation between prestress and dielectric behavior; the structure and performance of the LTSF/CC system can be effectively evaluated by dielectric analysis.</p>