The invention discloses an auxiliary mechanical linkage lock. The auxiliary mechanical linkage lock comprises a lock case, an upper pull rod, a lower pull rod, a pull rod driving mechanism and a pull rod fixing mechanism. The upper pull rod is connected with an upper bolt, the lower pull rod is connected with a lower bolt, the upper pull rod and the lower pull rod are connected through a gear and rack transmission assembly, and a cavity used for containing a latch of a main lock is formed between the upper pull rod and the lower pull rod. The pull rod driving mechanism is used for driving the upper pull rod and the lower pull rod to be simultaneously opened or closed in the longitudinal direction, and the pull rod fixing mechanism is used for fixing the opened upper pull rod and the opened lower pull rod. The pull rod driving mechanism comprises a driving wheel driven block, a driving wheel piece, a driving wheel and a first driving gear, wherein the driving wheel driven block, the driving wheel piece, the driving wheel and the first driving gear are coaxially arranged. The pull rod fixing mechanism comprises a fixing bolt, a second driving gear, a first cushion block, a bolt connecting piece, a first metal plate, a second metal plate and a bolt rack, wherein the first metal plate, the second metal plate and the bolt rack are fixed to the bottom surface of the bolt connecting piece. The auxiliary mechanical linkage lock is good in safety and anti-theft performance, has an automatic locking function and can improve the safety and anti-theft performance of an interior door when used in cooperation with the main lock installed on the interior door.