Abstract: Quantum entanglement has emerged as a transformative resource for surpassing the standard quantum limit in precision measurements. By harnessing non-classical correlations in the initial probe states, quantum-enhanced metrology enables measurement precision approaching the fundamental Heisenberg limit, thereby achieving unprecedented sensitivity. This paradigm has been successfully demonstrated across diverse quantum platforms, including ultracold atomic ensembles, trapped ion systems, and thermal atomic vapors, showcasing its broad applicability in pushing the boundaries of physical measurement and enabling next-generation quantum technologies. In this review, we presented a comprehensive theoretical framework for entanglement-enhanced quantum metrology, elucidating the fundamental role of quantum correlations in measurement enhancement. We systematically analyzed the generation and manipulation of entangled states for metrological applications. Furthermore, we highlighted state-of-the-art implementations of quantum sensors leveraging entanglement. Finally, current challenges and future directions were discussed in this rapidly evolving field, outlining promising avenues for both theoretical exploration and technological innovation.