A rotary cylinder assembly, including a rotary cylinder housing assembly and a spindle transmission assembly, wherein the spindle transmission assembly is arranged on one side of a latch or used individually; and a rotary cylinder housing assembly is arranged at the other end of the spindle transmission assembly and configured to drive the spindle transmission assembly under an external force to rotate to realize deadlocking. The rotary cylinder assembly drives the spindle transmission assembly by driving the rotary cylinder housing assembly to toggle the latch toggling sleeve to drive a bolt of the latch to extend, or drives a toggling adaptor of the spindle transmission assembly to directly hook or clamp a certain fixed part of a to-be-locked object, thereby realizing keyless mechanical deadlocking of the mechanical deadbolt lock.