The invention relates to an air conditioner outdoor machine and a protection device and a method thereof. The protection device of the air conditioner outdoor machine comprises a protection cover, a reel is arranged on a top cover of the air conditioner outdoor machine, the protection cover is arranged on the reel in a rolling mode, and the reel is connected with a reel driving motor. Before the air conditioner outdoor machine is operated, the air conditioner outdoor machine can achieve of automatically rolling the protection device up, and after the air conditioner outdoor machine stops working, the protection device can be automatically rolled down, and the aim that protection effect on the air conditioner outdoor machine can be achieved. If the air conditioner outdoor machine does not work, the air conditioner outdoor machine is protected by the protection cover, and when the protection cover is rolled up or rolled down, effectiveness is good. The air conditioner outdoor machine not only avoids the problem that manual installation of the protection cover is not convenient to operate, but also can avoid the problem that due to the fact that the protection cover is forgotten to installing, the air conditioner outdoor machine is damaged, or due to the fact that the protection cover is forgotten to remove, use of an air conditioner is affected. Simultaneously, the protection device is good in sealing effect, can prevent a foreign body from entering into the outdoor machine, ensures use effect of the air conditioner, and prolongs service life of the air conditioner.