The Shelter Island Conference is a famous conference in the history of science. The main topics are the divergence of quantum mechanics and the infinity of electromagnetic energy. The lamb experiment shows that the dilemma of quantum field theory is not an infinite quantity，but a finite and small quantity. The task of theoretical physicists is to prove that the quantity does exist. The renormalization scheme adopted by Betty and Feynman

and the Hamiltonian regular transformation method used by Schwinger make these difficulties solved. The new generation of physicists in the United States almost independently completed the creation of quantum electrodynamics. The success of this conference made the maturity of American Physics after the war.