This invention discloses a high strength security lock cylinder. The lock cylinder includes a front lock housing, a front lock plug, a rear lock housing, a rear lock plug, a horizontal bar, and a lock cam. The front and rear lock plugs are connected with the lock cam and can drive the lock cam to rotate. An electronic locking mechanism is placed inside the front lock plug. The rear lock plug is connected with an axel, which is connected with a knob that contains a digital control board and an electrical power source. A signal transmission channel is formed along the horizontal bar for transmitting signals between the electronic locking mechanism and the digital control board. The lock cylinder is flexible, strong, and resistant to drilling and lock picking and it can be digitally controlled. This reduces the security risks caused by misplacement or unauthorized use of keys.