Microwave electric fields play a vital role in a wide range of applications, including wireless communications, radar detection, navigation, and quantum information. The sensitivity of microwave field measurements directly determines a system’s capability to detect weak signals and its overall performance. Measurement sensitivity generally refers to a system’s ability to respond to minute variations in the measured physical quantity, serving as a key metric of precision and system performance. Conventional microwave measurement techniques are limited by antenna dimensions and the perturbation introduced by metallic structures, making it difficult to achieve high-precision detection of extremely weak signals. In recent years, Rydberg atoms—owing to their large electric dipole moments and high polarizability—have demonstrated exceptional sensitivity to microwave electric fields. This has significantly enhanced the system’s response to weak fields, overcoming the limitations of traditional approaches and offering promising prospects for future applications. This paper presents a comprehensive review of the principles and recent advances in Rydberg atom-based microwave electrometry, with a focus on physical mechanisms for sensitivity enhancement, key experimental breakthroughs, and emerging techniques such as cavity enhancement. Current challenges and future directions are also discussed to provide insights for further research and practical applications in this field.