The invention discloses a mechanical anti-theft lock applied to a well lid, an unlocking device and the well lid. The mechanical anti-theft lock applied to the well lid comprises a lock shell. A rotatable lock cylinder is arranged in the lock shell in a penetrating manner. The lock cylinder is fixedly connected with a spring bolt. The lock shell is provided with a first opening and a second opening, wherein a set included angle is formed between the first opening and the second opening. The spring bolt is driven by the lock cylinder to rotate to the first opening to be clamped and stopped, and then locking is completed. The spring bolt is driven by the lock cylinder to rotate to the second opening to be clamped and stopped, and then unlocking is completed. The top of the lock cylinder is a convex face. The lock cylinder is provided with at least one convex block in the radial direction around the convex face. The mechanical anti-theft lock applied to the well lid is provided with the two openings, locking and unlocking are completed at the two openings correspondingly, the locking manner is easy to operate, and the locked state or unlocked state is stable. According to the mechanical anti-theft lock applied to the well lid, the top of the lock cylinder driving the spring bolt to conduct unlocking or locking is set to be the convex face, and the convex blocks are arranged around the convex face; and in this way, common tools cannot be matched with the lock cylinder, so that a lock body cannot be unlocked through the common tools, and therefore the anti-theft effect is effectively achieved.