A refrigerant floating expansion apparatus including a main body, a standpipe, a float element and a separation element is provided. The main body includes a base plate and a pipe-shaped housing. The standpipe fixed on the base plate has a second pipe opening and a third pipe opening. The pipe wall of the standpipe has at least an opening near the second pipe opening. The float element surrounds the standpipe for controlling a fluid-passing area of the opening. The separation element surrounding the float element is disposed on the base plate and forms an inner path with the pipe-shaped housing. The separation element has several fluid passageways near the base plate. A high-pressure fluid entering the main body is guided to pass through the fluid passageways to move the float element for controlling the fluid-passing area of the opening. Then, the high-pressure fluid is transferred to a low-pressure fluid.