The invention provides a ventilator device for a pirate prevention security cabin of a ship, which comprises an air duct, a hood and a connecting rod. The hood is of a hollow structure and is arranged at the upper part of the air duct; a weather proof cover is arranged in the hood and the weather proof cover covers the upper end port of the air duct; the connecting rod is arranged in the air duct; one end of the connecting rod extends out of the hood after being screwed with the weather proof cover, and is provided with an outer handwheel; and the other end of the connecting rod passes through the bottom or the lateral part of the air duct and is provided with an inner handwheel, wherein the lower end part of the connecting rod is also provided with a locking device and the bottom of the hood is provided with an air inlet and a protection grid. According to the invention, a ventilator can be opened or closed inside and outside the cabin; and under the condition of pirate attack, the air duct can be locked in the security cabin so as to fulfill the aim of protecting boatmen and properties.