The invention relates to a protective device for the top of an inclinometer pipe and a protective method thereof. The device comprises an iron cylinder (2) and a cylinder sack (3). At first, the iron cylinder (2) is sleeved on the top of the inclinometer pipe (1); and secondly, the cylinder sack (3) is sleeved outside the iron cylinder (2) and lubricant is coated between the iron cylinder (2) andthe cylinder sack (3). The iron cylinder (2) can protect the inclinometer pipe (1) from being damaged when pile heads are splited and top beams are prepared. The cylinder sack (3) can prevent concretes and the iron cylinder (2) from bonding together. The lubricant between the iron cylinder (2) and the cylinder sack (3) can ensure that the iron cylinder (2) can be smoothly pulled out. The invention has simple structure, easy operation, good practical effect and lowered cost, and is suitable for protecting the inclinometer pipe from being damaged.