Abstract: In order to solve the problem of convergence instability of two-dimensional / one-dimensional neutron transport calculation, the first collision compensation for leakage source technique is proposed. The source term is equivalent to the scattering source of each region by the first collision method, which is equivalent to distributing the local isolated source into the whole wide space, so as to reduce the influence of the radiation effect of the leakage source. The single energy correction method is applied to simplify the calculation, and to improve the convergence, stability and accuracy of the two-dimensional / one-dimensional neutron transport calculation.