The invention discloses a structure conducting secondary lining finished product protection on an underground engineering lining constructed in parts. Underground engineering adopts the sequence thatthe two sides are excavated firstly and then the middle is excavated to conduct excavation on an excavated section, after excavation of the left side and the right side from top to bottom in parts iscompleted, secondary linings are constructed along the left side wall of an excavated part on the left side and the right side wall of an excavated part on the right side correspondingly, after each section of secondary lining is constructed, a protective plate is bonded on the corresponding secondary lining immediately to conduct secondary lining finished product protection and muck backfilling is conducted timely, and construction of a next section of secondary lining, secondary lining finished product protection and muck backfilling are conducted; and except for an inverted arch part and anarch crown, the secondary linings of other backfilled parts all need to be subjected to secondary lining finished product protection, and the height of muck backfilling every time cannot exceed the height of the corresponding secondary lining. Meanwhile, the invention further provides a construction method conducting secondary lining finished product protection on the underground engineering lining constructed in parts. The finished product quality can be effectively protected, the engineering quality defects are reduced, the later-period repairing cost is reduced, and the future troubles ofcontract work delay and the like are avoided.