The invention discloses a floating variable-section pier/tower pile anticollision device, especially relating to a floating anticollision device able to protect variable-section piers/tower piles, where an anticollision body is separated into two left and right independent box bodies between which there is at least a guiding component running through vertical dividing surface and forming dynamic connection that the box bodies goes up and down with water level and are disconnected and connected at the dividing surface, and the two box bodies are connected into a whole, and the two box bodies slide along the outer surfaces of the protected piers/piles and always surround the protected piers/tower piles; and the guiding component is composed of guide pile and guide sleeve; the positions of the inner surfaces of the two box bodies corresponding to the outer surfaces of the piers/piles are equipped with isolating components. And the invention has features of reasonable design, simple structure and achieving remarkable technical effects. And it can be applied to anticollision protection to various variable-section piers/tower piles. And it can prevent the sailing ships or other floatersfrom colliding piers/tower piles, having long service life and convenient to maintain and repair.