The invention relates to a maintenance method for shield equipment and discloses a method for replacing a tail brush in a shield tunnel through liquid nitrogen freezing. The method comprises the following processing steps: 1, preparation of construction; 2, construction of freezing holes; 3, installation of a freezing system and a temperature measuring system; 4, construction of liquid nitrogen freezing; 5, construction of sealing maintenance of a shield tail; 6, construction of formation sealing of the freezing holes; 7, construction of forced thawing; and 8, construction of propulsion of shield recovery. According to the invention, stratum is frozen through a liquid nitrogen freezing method to form a frozen curtain, so that the defect of indeterminacy of a traditional grouting method for carrying out the treatment of stratum consolidation and water sealing to bearing pressure permeable stratum can be avoided; and the method has the advantages of high strength, good uniformity, good water-resisting property and the like.