The invention relates to a smart coded lock for a bicycle and belongs to the technical field of bicycles and electric bicycles. The smart coded lock comprises a lock cylinder, a spring, a battery, a circuit board, a lock pin, a motor, a locking mechanism, a display panel, a digital keyboard, a lock upper cover and a lock lower cover, wherein the lock upper cover and the lock lower cover are matched with each other. The spring, the battery, the circuit board, the lock pin, the motor and the locking mechanism are fixed in the lock lower cover; the display panel and the digital keyboard are arranged on the lock upper cover; and the circuit board is connected with the battery, the motor, the display panel and the digital keyboard. The invention further provides a smart coded lock system used for the bicycle and convenient to use and an operation method thereof. The smart coded lock is reasonable in structure, safe and reliable, a password is variable, and whether a user has locked the bicycle can be detected when he returns the bicycle.