China′s tunneling industry is advancing toward greater length, larger dimensions, and deeper excavations. The authors review the evolution of tail seal technology in light of this trend and recent developments in domestic shield machines. The causes of tail seal failures are analyzed, the current research status both domestically and internationally is summarized, and adaptive research pathways are explored. The main conclusions are as follows: (1) The tail seal system is a dynamic, multi-field coupled system that is influenced by the interplay of four factors: material properties, geological conditions, operational practices, and tail structure. A notable example is the Foshan Metro "2·7" incident, where seal failure resulted from a combination of these factors. (2) Significant advancements have been made in key areas such as high-precision multi-point pressure monitoring of tail seals, stiffness testing of tail brushes, and assessment of critical grease properties that include water-pressure resistance, pumpability, and consistency. In addition, tail seal testing equipment now accommodates water pressures from conventional levels up to ultra-high pressures of 3.00 MPa. (3) Insights from brush seal research in turbomachinery are valuable, but optimization is necessary to meet the unique characteristics of tail seals. To address challenges associated with ultra-high water pressure and complex operating conditions, future breakthroughs should focus on the following: (1) Conducting multi-field coupled simulations to create a fluid-structure interaction modeling framework that reveals the mechanisms behind grease failure; (2) Developing grease products tailored for ultra-high water pressure, standardizing test parameters for evaluating water-pressure resistance, incorporating viscoelastic dynamic indicators into grease selection criteria, and establishing national standards for assessing grease physicochemical performance; (3) Optimizing existing brush structures to address issues such as brush hardening, thereby enhancing service life and sealing performance; and (4) Utilizing sensing elements such as surface pressure sensors to monitor the entire pressure field within the seal chamber and advancing digital twin technology in tail seal applications for dynamic condition mapping and lifespan prediction, thus ensuring safe tunneling operations.