The Hamiltonization of Birkhoffian systems was studied .A new method and the corresponding conditions for the transformation of Birkhoffian systems into Hamiltonian ones were presented. The approach to the construction of Hamiltonian for the Birkhoffian systems by means of the gauge transformations and the transformations of the variables was given.It was pointed out that Hamiltonization for all second order regular Birkhoffian systems can be realized.Two examples were given to illustrate the application of the results.