The invention discloses a telescopic vertical adjustment structure for thickness of a background wall with a lamp groove and belongs to the technical field of building construction. The structure comprises a wall body and an auxiliary keel, wherein a gypsum board is mounted between the wall body and the auxiliary keel, an edge hooking limit adjustment plate is mounted at the left end of the gypsumboard, and a lamp groove keel is mounted at the left end of the edge hooking limit adjustment plate. The invention also discloses a mounting process of the structure. The mounting process comprises the following steps: mounting and fixing of a partition keel; cutting production of the auxiliary keel; fixed mounting by fixing rivets; positioning fixing of a power pipe; clamping mounting of the power pipe. The structure is reasonable and novel in design, through cooperation of the edge hooking limit adjustment plate and the lamp groove keel, lamp mounting in the whole background wall is very convenient, the structure can be freely adjusted forwards and backwards when junction box models are different, used materials are uniform, fireproof and firm, and the structure is high in practicability and high in reliability.