Abstract: The failures of shield tail sealing have occurred from time to time, which may result in water and sand-gushing accidents in severe cases. This phenomenon has attracted great attention from the engineering and academic circles. According to the tests of dynamic compression and sealing grease escape of shield tail brushes, the results show that: (1) The dynamic compression tests can reflect the mechanical properties of the shield tail brushes, and save the test time greatly. (2) With the decrease of the shield tail gap, the adhesion force and elastic coefficient of the shield tail brushes increase continuously, the proportion of plastic deformation increases, and that of elastic deformation decreases. When the shield tail gap is 110 mm, the proportion of elastic deformation is 90%, and when it is compressed to 50 mm, the proportion of elastic deformation reduces to 60%. (3) The relationship among the gap, grease escape and adhesion force of shield tail is established, and the working safety area of the shield tail sealing system is obtained so as to evaluate the effectiveness of the status of shield tail sealing. The evaluation method for the performance of shield tail sealing is established, and can provide a reference for the performance evaluation and detection of the shield tail brushes.