The invention discloses a tunnel secondary lining maintenance device and method for a construction site in a limiting temperature step difference value. The tunnel secondary lining trolley (1) is used as a supporting body, the maintenance sealing interval
assembly is arranged between the tunnel secondary lining trolley (1) and a tunnel secondary lining body, the spraying device (13) is arranged between the maintenance sealing interval
assembly and the tunnel secondary lining trolley (1), and the steam generator (8) is arranged between the maintenance sealing interval
assembly and the tunnel secondary lining trolley (1). The tunnel secondary lining trolley (1) is provided with a maintenance sealing interval assembly, the
fog making device (9) is arranged between the maintenance sealing interval assembly and the tunnel secondary lining trolley (1), through the tunnel secondary lining trolley (1) and the maintenance sealing interval assembly, a maintenance sealing interval is prevented on a tunnel secondary lining body, through a spraying device (13), the tunnel secondary lining body is treated in a saturated
water body state, and through a steam generator (8) and the
fog making device (9), the maintenance sealing interval is prevented from being generated on the tunnel secondary lining body. A high-temperature and high-
humidity curing environment is created for the tunnel secondary lining body, the tunnel secondary lining body is subjected to upper part
permeation and maintenance water supplementation in a low-temperature state, and
cement particles are fully hydrated in rising high-temperature and high-
humidity steam mist clusters; the tunnel secondary lining maintenance device solves the technical problem that the tunnel secondary lining body is maintained by manually spraying water or covering wet cloth, so that the maintenance requirement of the tunnel secondary lining in a construction site at a limit temperature step difference value is met.