The invention discloses a novel smoke detector fixing device. The novel smoke detector fixing device comprises a fixed seat, a fixed plate, and a spool which is fixed on an outer wall of the fixed seat, wherein a smoke detector is arranged below the fixed plate; an outer surface of the smoke detector is provided with a protection shell; a top surface of the protection shell is fixedly connected with a bottom surface of the fixed plate; a lock rod is arranged in the middle of a top end of the fixed plate; a fastening cavity is formed in a lower segment of the lock rod; a concave part is arranged in the fixed plate at a lower end of the fastening cavity; a guide slide bar which extends into the fastening cavity and is fixedly connected with a top wall in the fastening cavity is arranged in the concave part; the guide slide bar is provided with a fastening block; a first tension spring is arranged around the guide slide rod at a lower end of the fastening block; outer walls of two sides of an upper segment of the lock rod are provided with locking holes correspondingly; a diagonal head part is arranged at a top end of the lock rod. The novel smoke detector fixing device has the advantages of simple structure, convenience in assembling and disassembling, and capability of lowering the climbing difficulty of disassembly-assembly personnel, and meanwhile the security of workers is improved.