The invention provides an underwater helicopter. A main body part of the underwater helicopter is composed of an upper cover, a lower cover, thrusters, a titanium ring, a control barrel, a fixing frame, welding blocks, connecting blocks, fixing blocks and screw rods. The control barrel is fixed to the fixing frame. The welding blocks are welded to the tail ends of supporting rods of the fixing frame. The welding blocks, the connecting blocks and the titanium ring are fixed through bolts and nuts. The upper cover, the lower cover and the titanium ring are fixed with bolts penetrating through through holes. If the underwater helicopter needs to dive downwards or float upwards, only the horizontally-upward thrusters need to be controlled to rotate; if the underwater helicopter needs to go forward or backward, only the horizontal thrusters need to be controlled to rotate in a forward and reverse mode; and if the underwater helicopter needs to hover, only the horizontally-upward thrusters need to be controlled to offset the underwater mass of the underwater helicopter at the certain rotating speed. The underwater helicopter is easy and convenient to operate and very flexible.