This invention discloses a small wave packet multi-carrier amplifying-frequency system based on neural net balancer and its controlling method. The system comprises a transmitting end composed of a quad-rature modulator, a copier, an inverse small wave packet conversion with an amplifying frequency code inserted before; a receiving end composed of multi-radial neural net balance, discrete small wave packet conversion, summer, a maximum likelihood tester and quad-rature modulator; after the conversion, inserting amplifying frequency code WH and sub-belt gain factor. The system owes a control switch to control its dislocation to realize using LMS method to renewing weight of multiradial neural net balancer and the communication of the sender and receiver, including channel balance, amplifying frequency, small wave packet multi-carrier adjusting, modulation and ML testing decision.