This invention provides a flexible antenna module for wireless energy transmission, which uses an antenna size controlling device to adjust the antenna's size to conform a living body's outer portion wearing the flexible annular antenna. An antenna energy transmission control module is provided to adjust the power for driving the flexible annular antenna according to the deformation of the flexible annular antenna. This invention can adjust both the antenna size to fit the individual and the power for driving the antenna. The individual can use the present antenna module under a comfortable, safe and reliable circumstance.